A030988 5-automorphic numbers: final digits of 5n^2 agree with n.

5, 25, 125, 8125, 78125, 578125, 2578125, 42578125, 642578125, 3642578125, 83642578125, 983642578125, 1983642578125, 51983642578125, 251983642578125, 1251983642578125, 51251983642578125

Offset

1,1

Comments

a(n) is the unique positive integer less than 10^n such that a(n) is divisible by 5^n and 5*a(n) - 1 is divisible by 2^n. - Eric M. Schmidt, Aug 18 2012

Links

Eric M. Schmidt, Table of n, a(n) for n = 1..1000

Index entries for sequences related to automorphic numbers

Index entries for sequences related to final digits of numbers

Eric Weisstein's World of Mathematics, Automorphic Number

Prog

(Sage) [crt(inverse_mod(5, 2^n), 0, 2^n, 5^n) for n in range(1, 1001)] # Eric M. Schmidt, Aug 18 2012

Crossrefs

Sequence in context: A306570 A061835 A321288 * A173260 A080516 A033141

Adjacent sequences: A030985 A030986 A030987 * A030989 A030990 A030991

Keyword

nonn,base

Author

Eric W. Weisstein

Status

approved