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.

A161993 A006005 (shifted) convolved with all of its regularly "aerated" variants.

Original entry on oeis.org

1, 3, 8, 19, 43, 85, 171, 315, 580, 1022, 1766, 2982, 4959, 8081, 12997, 20596, 32261, 49909, 76447, 115872, 174133, 259312, 383206, 561877, 818225, 1183266, 1700658, 2429266, 3450562, 4874167, 6850072, 9578548, 13331445, 18469783, 25478494, 34999375, 47887091
Offset: 0

Views

Author

Gary W. Adamson, Jun 24 2009

Keywords

Comments

Refer to A161779 for the analogous sequence based on the factorials.
Given A006005 (1 together with the odd primes = odd noncomposite numbers) = a, then b = the aerated variant: (1, 0, 3, 0, 5, 0, 7,...); c = (1, 0, 0, 3, 0, 0, 5,...) and so on such that A161993 = the infinite convolution product: a*b*c*...

Crossrefs

Programs

  • Maple
    p:= n-> `if`(n=0, 1, ithprime(n+1)):
    b:= proc(n, i) option remember; `if`(i>n, 0,
         `if`(irem(n, i, 'r')=0, p(r), 0)+
          add(p(j)*b(n-i*j, i+1), j=0..n/i))
        end:
    a:= n-> `if`(n=0, 1, b(n, 1)):
    seq(a(n), n=0..45);  # Alois P. Heinz, Jul 27 2019
  • Mathematica
    p[n_] := If[n==0, 1, Prime[n+1]];
    b[n_, i_] := b[n, i] = If[i>n, 0, If[Mod[n, i]==0, p[n/i], 0] + Sum[p[j] b[n - i j, i+1], {j, 0, n/i}]];
    a[n_] := If[n==0, 1, b[n, 1]];
    a /@ Range[0, 45] (* Jean-François Alcover, Nov 20 2020, after Alois P. Heinz *)

Extensions

Definition and comment corrected by Omar E. Pol, Aug 18 2011
Correct offset and a(13)-a(36) from Alois P. Heinz, Jul 27 2019