A374851 Obverse convolution A000040**A000040; see Comments.

4, 25, 294, 5184, 169000, 6350400, 331218944, 18517766400, 1288408000000, 124147372916736, 12047030383804416, 1481741383824000000, 199987846858565222400, 26836516406718627840000, 3937581724026934119628800, 668393794316928024576000000, 130212266115912538521600000000, 25085181032622344612780605440000

Offset: 1

Author

Clark Kimberling, Aug 05 2024

Keywords

• nonn

Comments

See A374848 for the definition of obverse convolution and a guide to related sequences. a(2k+1) is a square for k>=0. Conjecture: every positive integer divides a(n) for infinitely many n.

Crossrefs

Cf. A000040, A374848.

Programs

Mathematica

s[n_] := Prime[n]; t[n_] := Prime[n];
u[n_] := Product[s[k] + t[n + 1 - k], {k, 1, n}]
Table[u[n], {n, 1, 18}]