A033881 Abundancy of n-th abundant number: sigma(k) - 2k for k such that this is > 0.

4, 3, 2, 12, 12, 19, 10, 12, 28, 12, 8, 48, 12, 4, 51, 12, 26, 56, 4, 54, 60, 17, 12, 2, 64, 24, 12, 120, 60, 72, 12, 56, 115, 72, 80, 58, 39, 144, 12, 20, 186, 12, 124, 7, 72, 65, 96, 18, 156, 168, 64, 12, 56, 104, 78, 264, 12, 224, 12, 68, 192, 180, 14, 120, 160, 12, 243

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Formula

a(n) = A033880(A005101(n)). - Amiram Eldar, Apr 06 2024

Maple

with(numtheory): for n from 2 to 500 do if sigma(n) - 2*n > 0 then printf(`%d, `, sigma(n) - 2*n) fi: od:

Mathematica

Select[Table[DivisorSigma[1, n]-2n, {n, 300}], #>0&] (* Harvey P. Dale, May 21 2020 *)

Prog

(PARI) lista(kmax) = {my(ab); for(k = 1, kmax, ab = sigma(k)-2*k; if(ab > 0, print1(ab, ", "))); } \\ Amiram Eldar, Apr 06 2024

Crossrefs

Cf. A000203, A005101, A033880, A033884.

Sequence in context: A062111 A181596 A182142 * A099406 A274601 A202696

Adjacent sequences: A033878 A033879 A033880 * A033882 A033883 A033884

Keyword

nonn,changed

Author

N. J. A. Sloane

Extensions

More terms from James A. Sellers, Feb 19 2001

Status

approved