OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..66
EXAMPLE
a(7) = 1 + a(1)*a(2)*a(3)*a(6) = 1 + 1*2*3*10 = 61.
MATHEMATICA
Nest[Append[#1, 1 + Times @@ #1[[Divisors[#2] ]] ] & @@ {#, Length[#]} &, {1}, 21] (* Michael De Vlieger, Apr 13 2021 *)
PROG
(PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, my(d=divisors(n-1)); va[n] = 1 + prod(k=1, #d, va[d[k]]); ); va; } \\ Michel Marcus, Apr 13 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Feb 27 2002
STATUS
approved