A275588 a(1) = 1; thereafter a(n) = (Sum_{k=1..n-1} a(k)) ^ Product_{k=1..n-1} a(k).

1, 1, 2, 16, 429496729600000000000000000000000000000000

Offset

1,3

Comments

a(6) is roughly 10^(5.72199*10^44).

Links

Table of n, a(n) for n=1..5.

Example

a(4) = (a(1) + a(2) + a(3)) ^ (a(1)*a(2)*a(3)) = (1 + 1 + 2)^(1*1*2) = 4^2 = 16.

Mathematica

a[1] = 1; a[n_] := a[n] = Sum[a[k], {k, n - 1}]^Product[a[k], {k, n - 1}]; Table[a[n], {n, 0, 5}] (* Michael De Vlieger, Aug 04 2016 *)

Prog

(PARI) a(n) = if(n==1, 1, if(n>1, sum(k=1, n - 1, a(k)) ^ prod(k=1, n - 1, a(k))))

Crossrefs

Cf. A275587.

Sequence in context: A325048 A068916 A093987 * A114560 A108883 A199295

Adjacent sequences: A275585 A275586 A275587 * A275589 A275590 A275591

Keyword

nonn

Author

Rick L. Shepherd, Aug 02 2016

Status

approved