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A030984 2-automorphic numbers: final digits of 2*n^2 agree with n. 1
8, 88, 688, 4688, 54688, 554688, 3554688, 93554688, 893554688, 893554688, 40893554688, 40893554688, 40893554688, 70040893554688, 870040893554688, 1870040893554688, 71870040893554688, 871870040893554688 (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) is divisible by 2^n and 2*a(n) - 1 is divisible by 5^n. - Eric M. Schmidt, Aug 18 2012

LINKS

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

Eric Weisstein's World of Mathematics, Automorphic Number

Index entries for sequences related to automorphic numbers

Index entries for sequences related to final digits of numbers

PROG

(Sage) [crt(0, (5^n + 1)/2, 2^n, 5^n) for n in range(1, 1001)] # Eric M. Schmidt, Aug 18 2012

CROSSREFS

Sequence in context: A299671 A299749 A300263 * A109021 A271939 A043043

Adjacent sequences:  A030981 A030982 A030983 * A030985 A030986 A030987

KEYWORD

nonn,base,changed

AUTHOR

Eric W. Weisstein

STATUS

approved

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Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)