A045770 Numbers k such that sigma(k) == 8 (mod k).

1, 10, 49, 56, 368, 836, 11096, 17816, 45356, 77744, 91388, 128768, 254012, 388076, 2087936, 2291936, 13174976, 29465852, 35021696, 45335936, 120888092, 260378492, 381236216, 775397948, 3381872252, 4856970752, 6800228816, 8589344768, 44257207676, 114141404156, 1461083549696, 1471763808896, 2199013818368

Offset

1,2

Comments

a(31) > 10^12. - Donovan Johnson, Mar 01 2012

a(34) > 10^13. - Giovanni Resta, Apr 02 2014

Every number of the form 2^(j-1)*(2^j - 9), where 2^j - 9 is prime, is a term. - Jon E. Schoenfield, Jun 02 2019

Links

Jud McCranie, Table of n, a(n) for n = 1..35

Mathematica

Join[{1}, Select[Range[8000000], Mod[DivisorSigma[1, #], #]==8 &]] (* Vincenzo Librandi, Mar 11 2014 *)

Prog

(PARI) is(n)=sigma(n)%n==8 || n==1 \\ Charles R Greathouse IV, Mar 09 2014

Crossrefs

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

Sequence in context: A126734 A264266 A048698 * A217165 A154066 A056578

Adjacent sequences: A045767 A045768 A045769 * A045771 A045772 A045773

Keyword

nonn

Author

Dan Hoey

Extensions

Extended by T. D. Noe, Apr 06 2011

Initial term 1 added and a(26)-a(30) from Donovan Johnson, Mar 01 2012

a(31)-a(33) from Giovanni Resta, Apr 02 2014

Status

approved