1,1

For n=4, 2(2^1 - 1)*(2^2 - 1)*(2^3 -1)*(2^4 - 1) + 1 = 2*1*3*7*15 + 1 = 631

Sequence in context: A096843 A162455 A143684 this_sequence A050639 A100837 A019011

Adjacent sequences: A156890 A156891 A156892 this_sequence A156894 A156895 A156896

nonn

J. M. Bergot (thekingfishb(AT)yahoo.ca), Feb 17 2009