OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..350
EXAMPLE
a(0) = 1.
a(1) = 2.
a(2) = 2*3 + 1 = 7.
a(3) = 2*3*5 + 3 = 33.
a(4) = 2*3*5*7 + 3*5 + 1 = 226.
a(5) = 2*3*5*7*11 + 3*5*7 + 5 = 2420.
MAPLE
b:= proc(n, k) option remember;
`if`(n=k, 1, b(n-1, k)*ithprime(n))
end:
a:= n-> add(b(n-j, j), j=0..n/2):
seq(a(n), n=0..20);
MATHEMATICA
b[n_, k_] := b[n, k] = If[n == k, 1, b[n - 1, k]*Prime[n]];
a[n_] := Sum[b[n - j, j], {j, 0, n/2}];
Table[a[n], {n, 0, 20}] (* Jean-François Alcover, May 08 2022, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jan 21 2022
STATUS
approved