

A224473


(2*5^(2^n)  1) mod 10^n: a sequence of trimorphic numbers ending in 9.


6



9, 49, 249, 1249, 81249, 781249, 5781249, 25781249, 425781249, 6425781249, 36425781249, 836425781249, 9836425781249, 19836425781249, 519836425781249, 2519836425781249, 12519836425781249, 512519836425781249, 4512519836425781249, 84512519836425781249
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OFFSET

1,1


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 * A007185(n)  1) mod 10^n.


PROG

(Sage) def A224473(n) : return crt(1, 1, 2^n, 5^n);


CROSSREFS

Cf. A033819. Corresponding 10adic number is A091661. The other trimorphic numbers ending in 9 are included in A002283, A198971 and A224475.
Sequence in context: A228018 A081655 A181539 * A146798 A055428 A012231
Adjacent sequences: A224470 A224471 A224472 * A224474 A224475 A224476


KEYWORD

nonn,base


AUTHOR

Eric M. Schmidt, Apr 07 2013


STATUS

approved



