A097498 Numbers k divisible by their abundance sigma(k) - 2*k.

1, 2, 4, 8, 10, 12, 16, 18, 20, 24, 32, 40, 44, 56, 64, 88, 104, 120, 128, 136, 152, 184, 196, 224, 234, 256, 368, 464, 512, 650, 672, 752, 884, 992, 1024, 1504, 1888, 1952, 2048, 2144, 2272, 2528, 3724, 4096, 5624, 8192, 8384, 9112, 11096, 12224, 13736

Offset: 1

Author

Reinhard Zumkeller, Aug 24 2004

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..417 (terms 1..348 from Charles R Greathouse IV)
• Eric Weisstein's World of Mathematics, Abundance.

Crossrefs

Cf. A000079 (subsequence), A033879, A033880.

Disjoint union of A153501 and A271816.

Cf. also A379236.

Programs

Mathematica

Select[Range[15000],Divisible[#,DivisorSigma[1,#]-2#]&]//Quiet (* Harvey P. Dale, Mar 15 2018 *)

PARI

is(n)=my(t=sigma(n)-2*n); t && n%t==0 \\ Charles R Greathouse IV, Dec 12 2014