A198864 a(0) = 1; a(n) = n + product_{i=0..n-1} a(i), n >= 1.

1, 2, 4, 11, 92, 8101, 65585702, 4301483913318599, 18502763856538658405109886092616, 342352270330833327273885765082712290623512199361069533040982537

Offset

0,2

Comments

The product of an empty set is 1, so a(0) = 1.

5 - (1+1/2+1/4+1/11+1/92) = 3.14822... is close to Pi.

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 0..14

Formula

a(n) = n + a(0)*a(1)*...*a(n-1).

Mathematica

lst = {}; k = m = 1; Do[k = k*m; AppendTo[lst, k + n]; m = k + n, {n, 0, 9}]; lst

Crossrefs

Sequence in context: A327484 A006894 A193565 * A038093 A057284 A156463

Adjacent sequences: A198861 A198862 A198863 * A198865 A198866 A198867

Keyword

nonn

Author

Arkadiusz Wesolowski, Oct 30 2011

Status

approved