cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A258358 Sum over all partitions lambda of n into 3 distinct parts of Product_{i:lambda} prime(i).

Original entry on oeis.org

30, 42, 136, 293, 551, 892, 1765, 2570, 4273, 6747, 9770, 13958, 21206, 28280, 39702, 54913, 72227, 94682, 127095, 160046, 206119, 263581, 327790, 406354, 512372, 616764, 754412, 921169, 1100165, 1314196, 1584835, 1854384, 2191013, 2590565, 3006512, 3495086
Offset: 6

Views

Author

Alois P. Heinz, May 27 2015

Keywords

Crossrefs

Column k=3 of A258323.
Cf. A000040.

Programs

  • Maple
    g:= proc(n, i) option remember; convert(series(`if`(n=0, 1,
          `if`(i<1, 0, add(g(n-i*j, i-1)*(ithprime(i)*x)^j
          , j=0..min(1, n/i)))), x, 4), polynom)
        end:
    a:= n-> coeff(g(n$2), x, 3):
    seq(a(n), n=6..60);
  • Mathematica
    g[n_, i_] := g[n, i] = If[n == 0, 1, If[i < 1, 0, Sum[g[n - i j, i - 1] (Prime[i] x)^j, {j, 0, Min[1, n/i]}]]];
    a[n_] := Coefficient[g[n, n], x, 3];
    a /@ Range[6, 60] (* Jean-François Alcover, Dec 11 2020, after Alois P. Heinz *)