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A076496 Numbers k such that sigma(k) == 12 (mod k). 10
1, 24, 30, 42, 54, 66, 78, 102, 114, 121, 138, 174, 186, 222, 246, 258, 282, 304, 318, 354, 366, 402, 426, 438, 474, 498, 534, 582, 606, 618, 642, 654, 678, 762, 780, 786, 822, 834, 894, 906, 942, 978, 1002, 1038, 1074, 1086, 1146, 1158, 1182, 1194, 1266, 1338 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

6*p is a solution if p > 3 is prime, since sigma(6*p) = 1 + 2 + 3 + 6 + p + 2*p + 3*p + 6*p = 12*(p+1) = 2*6*p + 12 = 2*k + 12. These are "regular" solutions. Also k = 121, 304 are "singular" solutions. See other remainders in cross-references.

MATHEMATICA

Join[{1}, Select[Range[2000], Mod[DivisorSigma[1, #], #]==12 &]] (* Vincenzo Librandi, Mar 11 2014 *)

PROG

(PARI) is(n)=sigma(n)%n==12 \\ Charles R Greathouse IV, Mar 09 2014

CROSSREFS

Cf. A054024, A045768, A045769, A045770, A076495, A076496, A088834.

Sequence in context: A348604 A347063 A125639 * A125640 A141545 A106682

Adjacent sequences: A076493 A076494 A076495 * A076497 A076498 A076499

KEYWORD

nonn

AUTHOR

Labos Elemer, Oct 21 2002

EXTENSIONS

Initial term 1 added by Vincenzo Librandi, Mar 11 2014

STATUS

approved

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Last modified December 5 15:27 EST 2022. Contains 358588 sequences. (Running on oeis4.)