0,2

a(n)=(-1)^floor(n/2)/prod(i=1,2*n,cos(i*Pi/(2*n+1))^i)

(PARI) a(n)=2^(n*(2*n+1))

Sequence in context: A046242 A007117 A085533 this_sequence A076688 A004808 A047943

Adjacent sequences: A122064 A122065 A122066 this_sequence A122068 A122069 A122070

nonn

Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 15 2006