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oban numbers
A number  $n$  is called oban if its name (in English) does not contain the letter "o".

Assuming that the name of every power of 10 greater than  $10^5$  ends in "-illion" (like million, billion, trillion, etc.), then the oban numbers are finite. There are 454 of them, the largest begin 999.

Oban numbers belong to the same family of aban numbers, eban numbers, iban numbers, and uban numbers. All quite boring, if I may speak my mind...

As for the above sets, the definition is not really precise, since large numbers may have non-standard names.

The first oban numbers are 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 23, 25, 26, 27, 28, 29, 30, 33, 35, 36, 37, 38, 39, 50 more terms

Oban numbers can also be... (you may click on names or numbers and on + to get more values)

a-pointer 11 13 811 ABA 18 50 98 + 968 aban 10 11 12 + 999 abundant 12 18 20 + 996 Achilles 500 675 800 968 admirable 12 20 30 + 978 alt.fact. 19 619 alternating 10 12 16 + 989 amenable 12 13 16 + 997 apocalyptic 312 355 366 + 985 arithmetic 11 13 15 + 999 astonishing 15 27 automorphic 25 76 376 625 balanced p. 53 373 563 + 977 Bell 15 877 betrothed 75 binomial 10 15 20 + 990 brilliant 10 15 25 + 989 c.decagonal 11 911 c.heptagonal 316 386 638 + 953 c.nonagonal 10 28 55 + 820 c.octagonal 25 529 625 729 c.pentagonal 16 76 526 + 856 c.square 13 25 85 + 925 c.triangular 10 19 85 + 976 cake 15 26 93 + 988 Carol 959 Chen 11 13 17 + 983 congruent 13 15 20 + 999 constructible 10 12 15 + 960 cube 27 512 729 Cullen 25 65 385 897 Cunningham 10 15 17 + 999 Curzon 18 26 29 + 998 cyclic 11 13 15 + 997 D-number 15 33 39 + 993 d-powerful 63 89 333 + 935 de Polignac 337 373 509 + 997 decagonal 10 27 85 + 976 deceptive 703 deficient 10 11 13 + 999 dig.balanced 10 11 12 + 990 double fact. 15 droll 800 Duffinian 16 25 27 + 999 eban 30 36 50 + 66 economical 10 11 13 + 997 emirp 13 17 37 + 983 emirpimes 15 26 39 + 998 equidigital 10 11 13 + 997 eRAP 20 98 esthetic 10 12 23 + 989 Eulerian 11 26 57 66 evil 10 12 15 + 999 factorial 720 fibodiv 19 28 75 + 969 Fibonacci 13 55 89 + 987 Friedman 25 625 688 736 frugal 512 625 729 gapful 300 315 330 + 990 Gilda 29 78 330 + 997 Giuga 30 858 good prime 11 17 29 + 967 happy 10 13 19 + 998 harmonic 28 Harshad 10 12 18 + 999 heptagonal 18 55 616 + 970 hex 19 37 397 + 919 hexagonal 15 28 66 + 780 highly composite 12 36 60 + 720 hoax 58 85 308 + 985 Hogben 13 57 73 + 993 house 78 933 hungry 17 hyperperfect 28 325 697 iban 10 11 12 + 777 iccanobiF 13 39 836 idoneal 10 12 13 + 760 impolite 16 512 inconsummate 63 65 75 + 993 interprime 12 15 18 + 987 Jacobsthal 11 85 683 Jordan-Polya 12 16 36 + 960 junction 303 305 307 + 925 Kaprekar 55 99 703 999 katadrome 10 20 30 + 987 Kynea 23 79 Lehmer 15 85 511 + 763 Leyland 17 57 320 + 593 lonely 23 53 Lucas 11 18 29 76 lucky 13 15 25 + 997 Lynch-Bell 12 15 36 + 936 m-pointer 23 magic 15 65 369 + 870 magnanimous 11 12 16 + 998 metadrome 12 13 15 + 789 modest 13 19 23 + 999 Moran 18 27 63 + 999 Motzkin 323 835 narcissistic 370 nialpdrome 10 11 20 + 999 nonagonal 75 325 396 + 969 nude 11 12 15 + 999 O'Halloran 12 20 36 + 660 octagonal 65 96 560 + 936 odious 11 13 16 + 998 palindromic 11 33 55 + 999 palprime 11 313 353 + 929 pancake 11 16 29 + 667 panconsummate 10 11 12 + 523 pandigital 11 15 19 + 990 partition 11 15 30 + 627 pentagonal 12 35 70 + 925 perfect 28 pernicious 10 11 12 + 998 Perrin 10 12 17 + 853 Pierpont 13 17 19 + 769 plaindrome 11 12 13 + 999 power 16 25 27 + 900 powerful 16 25 27 + 968 practical 12 16 18 + 990 prim.abundant 12 18 20 + 978 prime 11 13 17 + 997 primeval 13 37 primorial 30 pronic 12 20 30 + 930 Proth 13 17 25 + 993 pseudoperfect 12 18 20 + 996 rare 65 repdigit 11 33 55 + 999 repfigit 19 28 75 repunit 13 15 57 + 993 Ruth-Aaron 15 16 25 + 715 Saint-Exupery 60 780 Sastry 328 528 715 self 20 53 75 + 995 semiprime 10 15 25 + 998 sliding 11 20 25 + 925 Smith 27 58 85 + 985 sphenic 30 66 70 + 987 square 16 25 36 + 900 star 13 37 73 + 937 straight-line 333 357 369 + 999 strobogrammatic 11 69 88 + 986 strong prime 11 17 29 + 967 super Niven 10 12 20 + 990 super-d 19 69 310 + 988 superabundant 12 36 60 + 720 tau 12 18 36 + 996 tetrahedral 10 20 35 + 969 tetranacci 15 29 56 773 triangular 10 15 28 + 990 tribonacci 13 927 trimorphic 25 75 76 + 999 truncatable prime 13 17 23 + 997 twin 11 13 17 + 883 uban 10 11 12 + 99 Ulam 11 13 16 + 986 undulating 303 313 323 + 989 unprimeable 320 325 326 + 898 untouchable 88 96 306 + 996 upside-down 19 28 37 + 753 wasteful 12 18 20 + 999 weak prime 13 19 23 + 997 weird 70 836 Woodall 17 23 63 + 895 Zuckerman 11 12 15 + 816 Zumkeller 12 20 28 + 996 zygodrome 11 33 55 + 999