A331073 a(n) = Sum_{k = 1..n} [d_3(k)*d_3(n+1-k)], where d_3 = A007425.

0, 1, 6, 15, 30, 51, 72, 114, 128, 207, 204, 315, 294, 465, 402, 622, 510, 834, 636, 1023, 834, 1251, 918, 1602, 1074, 1767, 1392, 2117, 1428, 2523, 1620, 2781, 2088, 3003, 2000, 3882, 2238, 3729, 2886, 4350, 2688, 5055, 2928, 5313, 3768, 5343, 3420, 7032, 3678, 6264, 4800, 7347, 4230, 8278, 4584, 8394

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, n}]; Array[a, 100, 0] (* Amiram Eldar, Apr 19 2024 *)

Crossrefs

Cf. A007425.

See A331074 for another version.

Sequence in context: A256874 A250121 A024802 * A011886 A212251 A262464

Adjacent sequences: A331070 A331071 A331072 * A331074 A331075 A331076

Keyword

nonn,changed

Author

N. J. A. Sloane, Jan 10 2020

Extensions

Offset corrected by Amiram Eldar, Apr 19 2024

Status

approved