A239899 a(0)=2, a(1)=5; thereafter a(n) = product of all preceding terms, minus 1.

2, 5, 9, 89, 8009, 64152089, 4115490587216009, 16937262773463574696951813104089

Offset

0,1

Links

Table of n, a(n) for n=0..7.

Robert Munafo, Some integer sequences

Robert Munafo, Mutually coprime sequences

Formula

a(n) == 8 mod 9, for n > 2. - Ivan N. Ianakiev, Apr 06 2014

a(n) = (a(n-1)+1)*a(n-1)-1, for n > 2. - Zak Seidov, Apr 06 2014

Example

(9 + 1)*9 - 1 = 89, (89 + 1)*89 - 1 = 8009, (8009 + 1)*8009 - 1 = 64152089. - Zak Seidov, Apr 06 2014

Prog

(Magma) I:=[2, 5, 9]; [n le 3 select I[n] else Self(n-1)*(Self(n-1)+1)-1: n in [1..10]]; // Vincenzo Librandi, May 22 2014

Crossrefs

Cf. A144779-A144784, A239900.

Sequence in context: A334986 A185160 A289942 * A188948 A334295 A083460

Adjacent sequences: A239896 A239897 A239898 * A239900 A239901 A239902

Keyword

nonn

Author

N. J. A. Sloane, Apr 05 2014

Status

approved