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oban numbers
A number    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    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 ABA aban abundant Achilles admirable alt.fact. alternating amenable apocalyptic arithmetic astonishing automorphic balanced p. Bell betrothed binomial brilliant c.decagonal c.heptagonal c.nonagonal c.octagonal c.pentagonal c.square c.triangular cake Carol Chen congruent constructible cube Cullen Cunningham Curzon cyclic D-number d-powerful de Polignac decagonal deceptive deficient dig.balanced double fact. droll Duffinian eban economical emirp emirpimes equidigital eRAP esthetic Eulerian evil factorial fibodiv Fibonacci Friedman frugal gapful Gilda Giuga good prime happy harmonic Harshad heptagonal hex hexagonal highly composite hoax Hogben house hungry hyperperfect iban iccanobiF idoneal impolite inconsummate interprime Jacobsthal Jordan-Polya junction Kaprekar katadrome Kynea Lehmer Leyland lonely Lucas lucky Lynch-Bell m-pointer magic magnanimous metadrome modest Moran Motzkin narcissistic nialpdrome nonagonal nude O'Halloran octagonal odious palindromic palprime pancake panconsummate pandigital partition pentagonal perfect pernicious Perrin Pierpont plaindrome power powerful practical prim.abundant prime primeval primorial pronic Proth pseudoperfect rare repdigit repfigit repunit Ruth-Aaron Saint-Exupery Sastry self semiprime sliding Smith Sophie Germain sphenic square star straight-line strobogrammatic strong prime super Niven super-d superabundant tau tetrahedral tetranacci triangular tribonacci trimorphic truncatable prime twin uban Ulam undulating unprimeable untouchable upside-down wasteful weak prime weird Woodall Zuckerman Zumkeller zygodrome