A number n such that n ± rev(n) are two squares. more
The rare numbers up to 10
15 :
65,
621770,
281089082,
2022652202,
2042832002,
868591084757,
872546974178,
872568754178,
6979302951885,
20313693904202,
20313839704202,
20331657922202,
20331875722202,
20333875702202,
40313893704200,
40351893720200,
200142385731002,
204238494066002,
221462345754122,
244062891224042,
245518996076442,
248359494187442,
403058392434500,
441054594034340,
816984566129618.
Distribution of the remainders when the numbers in this family are divided by n=2, 3,..., 11. (I took into account 84 values, from 65 to 6.5⋅1019).
n\r | 0 | 1 |
2 | 66 | 18 | 2 |
3 | 18 | 0 | 66 | 3 |
4 | 20 | 18 | 46 | 0 | 4 |
5 | 23 | 0 | 47 | 14 | 0 | 5 |
6 | 15 | 0 | 51 | 3 | 0 | 15 | 6 |
7 | 2 | 17 | 25 | 6 | 15 | 11 | 8 | 7 |
8 | 8 | 6 | 46 | 0 | 12 | 12 | 0 | 0 | 8 |
9 | 18 | 0 | 14 | 0 | 0 | 38 | 0 | 0 | 14 | 9 |
10 | 11 | 0 | 41 | 0 | 0 | 12 | 0 | 6 | 14 | 0 | 10 |
11 | 41 | 0 | 5 | 0 | 0 | 0 | 7 | 16 | 4 | 0 | 11 |
A pictorial representation of the table above
Imagine to divide the members of this family by a number n and compute the remainders. Should they be uniformly distributed, each remainder from 0 to n-1 would be obtained in about (1/n)-th of the cases. This outcome is represented by a white square. Reddish (resp. bluish) squares represent remainders which appear more (resp. less) frequently than 1/n.