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A067719 Numbers k such that sigma(k^2 + 1) == 0 (mod k). 1
1, 2, 3, 9, 12, 21, 33, 72, 93, 196, 228, 252, 360, 475, 850, 1458, 1725, 1752, 2100, 2241, 2584, 3007, 3404, 4347, 4743, 5544, 5720, 6555, 6600, 9909, 10512, 14175, 15507, 16680, 19404, 26460, 29008, 29484, 36003, 36400, 37107, 46728 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..100

MATHEMATICA

Select[Range[50000], Divisible[DivisorSigma[1, #^2+1], #]&] (* Harvey P. Dale, Nov 04 2011 *)

CROSSREFS

Sequence in context: A182203 A168080 A048084 * A057017 A330298 A330242

Adjacent sequences:  A067716 A067717 A067718 * A067720 A067721 A067722

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Feb 05 2002

STATUS

approved

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Last modified October 20 04:52 EDT 2021. Contains 348099 sequences. (Running on oeis4.)