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A224475 (2*5^(2^n) + (10^n)/2 - 1) mod 10^n: a sequence of trimorphic numbers ending (for n > 1) in 9. 4
4, 99, 749, 6249, 31249, 281249, 781249, 75781249, 925781249, 1425781249, 86425781249, 336425781249, 4836425781249, 69836425781249, 19836425781249, 7519836425781249, 62519836425781249, 12519836425781249, 9512519836425781249, 34512519836425781249 (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) + 2^(n-1) - 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) = (A224473(n) + 10^n / 2) mod 10^n.

PROG

(Sage) def A224475(n) : return crt(2^(n-1)+1, -1, 2^n, 5^n)

CROSSREFS

Cf. A033819. Converges to the 10-adic number A091661. The other trimorphic numbers ending in 9 are included in A002283, A198971, and A224473.

Sequence in context: A320358 A180830 A265721 * A091268 A326085 A158082

Adjacent sequences:  A224472 A224473 A224474 * A224476 A224477 A224478

KEYWORD

nonn,base

AUTHOR

Eric M. Schmidt, Apr 07 2013

STATUS

approved

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Last modified July 30 21:33 EDT 2021. Contains 346365 sequences. (Running on oeis4.)