A068334 a(1) = 1; a(n+1) = 1 + Product_{k|n} a(k), product is over the positive divisors, k, of n.

1, 2, 3, 4, 9, 10, 61, 62, 497, 1492, 26857, 26858, 6445921, 6445922, 786402485, 21232867096, 10531502079617, 10531502079618, 314049392014208761, 314049392014208762, 33736441887734362049089, 6173768865455388254983288

Offset: 1

Author

Leroy Quet, Feb 27 2002

Keywords

• nonn

Examples

			a(7) = 1 + a(1)*a(2)*a(3)*a(6) = 1 + 1*2*3*10 = 61.
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..66

Crossrefs

Cf. A068336, A343390.

Programs

Mathematica

Nest[Append[#1, 1 + Times @@ #1[[Divisors[#2] ]] ] & @@ {#, Length[#]} &, {1}, 21] (* Michael De Vlieger, Apr 13 2021 *)

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