A155104 Numbers appearing in the fourth column of A155103.

1, 5, 45, 765, 25245, 1640925, 211679325, 54401586525, 27908013887325, 28605714234508125, 58613108466507148125, 240137905387279785868125, 1967449858837983285617548125, 32236665937060356134843526028125

Offset: 1

Author

Mats Granvik, Jan 20 2009

Keywords

• nonn

Examples

			a(1)=1, a(2)=1*5, a(3)=1*5*9, a(4)=1*5*9*17, a(5)=1*5*9*17*33, a(6)=1*5*9*17*33*65 and so on. See A000051 for continuation.
		

Crossrefs

Cf. A000051, A155105.

Programs

Mathematica

Table[QPochhammer[-4, 2, n - 1], {n, 14}] (* Arkadiusz Wesolowski, Oct 29 2012 *)

Formula

a(n) = prod(k=2..n) (1+2^k), n>1. - Mats Granvik, Simone Severini, Dec 04 2010

a(n) = A028362(n+1)/3. - Vladimir Reshetnikov, Sep 16 2016

Extensions

More terms from Mats Granvik, Dec 05 2010