

A030990


7automorphic numbers ending in 3: final digits of 7n^2 agree with n.


1



3, 43, 143, 7143, 57143, 857143, 2857143, 42857143, 142857143, 7142857143, 57142857143, 857142857143, 2857142857143, 42857142857143, 142857142857143, 7142857142857143, 57142857142857143
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OFFSET

1,1


COMMENTS

a(n) is the unique positive integer less than 10^n such that 7a(n)  1 is divisible by 10^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
Index entries for linear recurrences with constant coefficients, signature (11,10,1000,11000,10000).


MATHEMATICA

LinearRecurrence[{11, 10, 1000, 11000, 10000}, {3, 43, 143, 7143, 57143}, 20] (* Harvey P. Dale, Apr 02 2018 *)


PROG

(Sage) [inverse_mod(7, 10^n) for n in xrange(1, 1001)] # Eric M. Schmidt, Aug 18 2012


CROSSREFS

Sequence in context: A003525 A042661 A281503 * A054698 A229695 A060559
Adjacent sequences: A030987 A030988 A030989 * A030991 A030992 A030993


KEYWORD

nonn,base


AUTHOR

Eric W. Weisstein


STATUS

approved



