A070682 - OEIS

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A070682

Smallest m in range 1..phi(2n+1) such that 10^m == 1 mod 2n+1, or 0 if no such number exists.

0, 1, 0, 6, 1, 2, 6, 0, 16, 18, 6, 22, 0, 3, 28, 15, 2, 0, 3, 6, 5, 21, 0, 46, 42, 16, 13, 0, 18, 58, 60, 6, 0, 33, 22, 35, 8, 0, 6, 13, 9, 41, 0, 28, 44, 6, 15, 0, 96, 2, 4, 34, 0, 53, 108, 3, 112, 0, 6, 48, 22, 5, 0, 42, 21, 130, 18, 0, 8, 46, 46, 6, 0, 42, 148

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..74.

PROG

(PARI) a(n) = {for (m = 1, eulerphi(2*n+1), if (10^m % (2*n+1) == 1, return (m)); ); return (0); } \\ Michel Marcus, Sep 14 2013

CROSSREFS

Cf. A070667-A070675, A002326, A070676, A053447, A070677, A070678, A053451, A070679, A070681, A070680, A070683.

Sequence in context: A090551 A220782 A274617 * A216415 A112828 A085766

Adjacent sequences: A070679 A070680 A070681 * A070683 A070684 A070685

KEYWORD

nonn

AUTHOR

N. J. A. Sloane and Amarnath Murthy, May 08 2002

STATUS

approved