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A067718 Numbers n such that sigma(2^n+1) == 0 (mod n). 0
1, 2, 6, 12, 24, 36, 42, 70, 126, 132, 144, 168, 210, 225, 252, 336, 344, 378, 385, 396, 462 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..21.

PROG

(PARI) for(n=1, 260, if(sigma(2^n+1)%n==0, print1(n, ", "))) \\ Klaus Brockhaus

CROSSREFS

Sequence in context: A194096 A099993 A011778 * A210594 A307252 A306625

Adjacent sequences:  A067715 A067716 A067717 * A067719 A067720 A067721

KEYWORD

nonn,hard,more

AUTHOR

Benoit Cloitre, Feb 05 2002

EXTENSIONS

a(13)-a(15) from Klaus Brockhaus Apr 13 2005

a(16)-a(21) from Lars Blomberg, Jul 28 2017

STATUS

approved

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Last modified October 22 04:25 EDT 2019. Contains 328315 sequences. (Running on oeis4.)