A331074 a(n) = Sum_{k = 1..ceiling(n/2)} [d_3(k)*d_3(n+1-k)], where d_3 = A007425.

0, 1, 3, 12, 15, 30, 36, 75, 64, 108, 102, 198, 147, 237, 201, 361, 255, 435, 318, 552, 417, 630, 459, 963, 537, 888, 696, 1099, 714, 1302, 810, 1503, 1044, 1506, 1000, 2103, 1119, 1869, 1443, 2337, 1344, 2568, 1464, 2697, 1884, 2676, 1710, 3966, 1839, 3150, 2400, 3714, 2115, 4189, 2292, 4359, 2943, 4098

Offset

0,3

Comments

For background references see A330570.

Links

Amiram Eldar, Table of n, a(n) for n = 0..10000

Mathematica

f[p_, e_] := (e+1)*(e+2)/2; s[1] = 1; s[n_] := s[n] = Times @@ f @@@ FactorInteger[n]; a[n_ := Sum[s[k] * s[n+1-k], {k, 1, Ceiling[n/2]}]; Array[a, 100, 0] (* Amiram Eldar, Apr 19 2024 *)

Crossrefs

Cf. A007425.

See A331073 for another version.

Sequence in context: A269315 A329575 A022380 * A290593 A005392 A001196

Adjacent sequences: A331071 A331072 A331073 * A331075 A331076 A331077

Keyword

nonn,changed

Author

N. J. A. Sloane, Jan 10 2020

Extensions

Offset and name corrected by Amiram Eldar, Apr 19 2024

Status

approved