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A030988 5-automorphic numbers: final digits of 5n^2 agree with n. 1
5, 25, 125, 8125, 78125, 578125, 2578125, 42578125, 642578125, 3642578125, 83642578125, 983642578125, 1983642578125, 51983642578125, 251983642578125, 1251983642578125, 51251983642578125 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 7 02:57 EST 2021. Contains 349567 sequences. (Running on oeis4.)