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.
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
a(n) = (2 * A016090(n) - 1) mod 10^n.
(Sage) def A224474(n) : return crt(-1, 1, 2^n, 5^n)
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
Eric M. Schmidt, Apr 07 2013