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A131644 a(n) = 2^(a(n-1)) mod n. +0
1
0, 1, 2, 0, 1, 2, 4, 0, 1, 2, 4, 4, 3, 8, 1, 2, 4, 16, 5, 12, 1, 2, 4, 16, 11, 20, 4, 16, 25, 2, 4, 16, 31, 26, 4, 16, 9, 18, 25, 32, 37, 2, 4, 16, 16, 32, 42, 16, 23, 8, 1, 2, 4, 16, 31, 16, 43, 56, 15, 8, 12, 4, 16, 0, 1, 2, 4, 16, 55, 58, 29, 32, 32, 44, 16, 24, 71, 20, 9, 32, 49, 20, 37 (list; graph; listen)
OFFSET

1,3

COMMENT

All positive integers seem to occur somewhere in this sequence (a proof would be nice!).

The first occurrence of 6 is a(59474). The first occurrence of 33 is a(2514233).

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

FORMULA

a(n) = 2^(a(n-1)) mod n, a(0) = 0

EXAMPLE

a(11) = 4, so a(12) = 2^a(11) mod 12 = 16 mod 12 = 4.

CROSSREFS

Sequence in context: A115218 A023858 A011118 this_sequence A115346 A140531 A117316

Adjacent sequences: A131641 A131642 A131643 this_sequence A131645 A131646 A131647

KEYWORD

easy,nonn,nice

AUTHOR

Jon Ayres (jonathan.ayres(AT)ntlworld.com), Sep 08 2007

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.


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