A331076 a(n) = Sum_{k = 1..ceiling(n/2)} [u_3(k)*u_3(n+1-k)], where u_3 = A034836.

0, 1, 1, 2, 3, 4, 5, 8, 8, 11, 11, 16, 16, 19, 18, 29, 24, 31, 28, 39, 34, 43, 36, 60, 44, 57, 49, 71, 55, 75, 61, 93, 73, 90, 71, 118, 83, 107, 93, 135, 95, 135, 102, 152, 118, 147, 112, 202, 126, 169, 145, 203, 139, 211, 147, 233, 177, 215, 160, 286

Offset

0,4

Comments

For background references see A330570.

Links

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

Mathematica

s[1] = 1; s[n_] := s[n] = Module[{e = FactorInteger[n][[;; , 2]]}, If[IntegerQ[Surd[n, 3]], 1/3, 0] + (Times @@ ((e + 1)*(e + 2)/2))/6 + (Times @@ (Floor[e/2] + 1))/2]; 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. A034836.

See A331075 for another version.

Sequence in context: A297694 A297637 A325415 * A316496 A332339 A100882

Adjacent sequences: A331073 A331074 A331075 * A331077 A331078 A331079

Keyword

nonn,changed

Author

N. J. A. Sloane, Jan 10 2020

Extensions

Offset and name corrected by Amiram Eldar, Apr 19 2024

Status

approved