A074376 s(3s-1)/2 where s is the sum of the prime factors of n (with repetition).

0, 5, 12, 22, 35, 35, 70, 51, 51, 70, 176, 70, 247, 117, 92, 92, 425, 92, 532, 117, 145, 247, 782, 117, 145, 330, 117, 176, 1247, 145, 1426, 145, 287, 532, 210, 145, 2035, 651, 376, 176, 2501, 210, 2752, 330, 176, 925, 3290, 176, 287, 210, 590, 425, 4187

Offset

1,2

Links

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

Neville Holmes, Integer Sequence Combinations [Broken link?]

Example

a(20) = 9(3*9-1)/2 = 117 because 9 = 2+2+5 and 20 = 2*2*5.

Mathematica

spf[n_]:=Module[{t=Total[Flatten[Table[#[[1]], #[[2]]]&/@FactorInteger[ n]]]}, (t(3t-1))/2]; Join[{0}, Array[spf, 60, 2]] (* Harvey P. Dale, Sep 23 2016 *)

Prog

(PARI) sopfr(n) = my(f=factor(n)); sum(k=1, matsize(f)[1], f[k, 1]*f[k, 2])
fn(n) = my(s=sopfr(n)); s*(3*s-1)/2 \\ Michel Marcus, Jul 11 2013

Crossrefs

Applies A000326 to A001414. Cf. A074373, A074374, A074375.

Sequence in context: A217649 A333578 A131976 * A293502 A134340 A000326

Adjacent sequences: A074373 A074374 A074375 * A074377 A074378 A074379

Keyword

easy,nonn

Author

W. Neville Holmes, Aug 29 2002

Status

approved