A274558 Numbers k such that sigma(k) == 0 (mod k-6).

5, 7, 13, 14, 20, 30, 45, 76, 630, 688, 2310, 8896, 133888, 537051136, 1631268870, 35184418226176, 144115191028645888, 2305843021024854016

Offset

1,1

Comments

Contains terms of A141549, odd terms of A141548 multiplied by 2, and 6 times terms of A191363 coprime to 6. - Max Alekseyev, May 25 2025

Links

Table of n, a(n) for n=1..18.

Example

sigma(7) mod (7-6) = 8 mod 1 = 0.

Mathematica

Select[Range[7, 10^6],  # - 6 != 0 && Mod[DivisorSigma[1, #], # - 6] == 0 &] (* Michael De Vlieger, Jul 05 2016 *)

Crossrefs

Contains subsequence A141549.

Cf. A000203, A045770, A067702, A088833, A141548, A181598, A191363, A274551, A274552, A274553, A274554, A274556, A274557, A274559, A274560, A274561, A274562, A274563, A274564, A274565, A274566.

Sequence in context: A166163 A249801 A386873 * A318346 A342715 A050079

Adjacent sequences: A274555 A274556 A274557 * A274559 A274560 A274561

Keyword

nonn,more

Author

Paolo P. Lava, Jul 05 2016

Extensions

a(14)-a(15) from Giovanni Resta

Term 5 inserted, a(16)-a(18) added by Max Alekseyev, Jun 04 2025

Status

approved