A014348 Three-fold exponential convolution of primes with themselves (divided by 2).

4, 18, 84, 393, 1830, 8433, 38376, 171957, 757362, 3271533, 13849980, 57396693, 233039058, 927277245, 3624209748, 13934877933, 52843565490, 197989340133, 734212702164, 2698456656933, 9837838481154, 35609804891973, 128026118332596, 457386991178451

Offset

0,1

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Maple

b:= proc(n, k) option remember; `if`(k=1, ithprime(n+1), add(
      b(j, floor(k/2))*b(n-j, ceil(k/2))*binomial(n, j), j=0..n))
    end:
a:= n-> b(n, 3)/2:
seq(a(n), n=0..30);  # Alois P. Heinz, Jun 07 2018

Mathematica

b[n_, k_] := b[n, k] = If[k==1, Prime[n+1], Sum[b[j, Floor[k/2]] b[n-j, Ceiling[k/2]] Binomial[n, j], {j, 0, n}]];
a[n_] := b[n, 3]/2;
a /@ Range[0, 30] (* Jean-François Alcover, Nov 16 2020, after Alois P. Heinz *)

Crossrefs

Cf. A014347.

Sequence in context: A218986 A143646 A290916 * A126020 A086405 A151251

Adjacent sequences: A014345 A014346 A014347 * A014349 A014350 A014351

Keyword

nonn

Author

N. J. A. Sloane.

Status

approved