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A224474 (2*16^(5^n) - 1) mod 10^n: a sequence of trimorphic numbers ending in 1. 6
1, 51, 751, 8751, 18751, 218751, 4218751, 74218751, 574218751, 3574218751, 63574218751, 163574218751, 163574218751, 80163574218751, 480163574218751, 7480163574218751, 87480163574218751, 487480163574218751, 5487480163574218751, 15487480163574218751 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 18 18:07 EST 2018. Contains 318243 sequences. (Running on oeis4.)