A224474 (2*16^(5^n) - 1) mod 10^n: a sequence of trimorphic numbers ending in 1.

1, 51, 751, 8751, 18751, 218751, 4218751, 74218751, 574218751, 3574218751, 63574218751, 163574218751, 163574218751, 80163574218751, 480163574218751, 7480163574218751, 87480163574218751, 487480163574218751, 5487480163574218751, 15487480163574218751

Offset

1,2

Comments

a(n) is the unique positive integer less than 10^n such that a(n) + 1 is divisible by 2^n and a(n) - 1 is divisible by 5^n.

Links

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

Eric Weisstein's World of Mathematics, Trimorphic Number

Index entries for sequences related to automorphic numbers

Formula

a(n) = (2 * A016090(n) - 1) mod 10^n.

Prog

(Sage) def A224474(n) : return crt(-1, 1, 2^n, 5^n)

Crossrefs

Cf. A033819. Corresponding 10-adic number is A063006. The other trimorphic numbers ending in 1 are included in A199685 and A224476.

Sequence in context: A231750 A232020 A210176 * A201140 A210079 A201832

Adjacent sequences: A224471 A224472 A224473 * A224475 A224476 A224477

Keyword

nonn,base

Author

Eric M. Schmidt, Apr 07 2013

Status

approved