OFFSET
1,2
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
EXAMPLE
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.
MATHEMATICA
Table[QPochhammer[-4, 2, n - 1], {n, 14}] (* Arkadiusz Wesolowski, Oct 29 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Mats Granvik, Jan 20 2009
EXTENSIONS
More terms from Mats Granvik, Dec 05 2010
STATUS
approved