A030991 7-automorphic numbers ending in 5: final digits of 7n^2 agree with n.

5, 75, 375, 4375, 84375, 984375, 8984375, 58984375, 458984375, 5458984375, 45458984375, 845458984375, 2845458984375, 22845458984375, 322845458984375, 2322845458984375, 22322845458984375

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 7a(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(7, 2^n), 0, 2^n, 5^n) for n in range(1, 1001)] # Eric M. Schmidt, Aug 18 2012

Crossrefs

Sequence in context: A380925 A285452 A048350 * A216093 A151752 A127212

Adjacent sequences: A030988 A030989 A030990 * A030992 A030993 A030994

Keyword

nonn,base

Author

Eric W. Weisstein

Status

approved