0,3
A variant of A005014. Equals row sums (unsigned) of triangle A214690.
Table of n, a(n) for n=0..12.
a(n) = 2*(4^(n-1) - 1)*a(n-1) - (-1)^n for n>0 with a(0)=1.
(PARI) {a(n)=if(n==0, 1, 2*(4^(n-1)-1)*a(n-1) - (-1)^n)}
(PARI) {a(n)=local(A=x); A=sum(m=0, n, x^m*prod(j=1, m, (2^(2*j-1)-1)/(1+x*2^(2*j-1))+x*O(x^n))); polcoeff(A, n, x)}
for(n=0, 20, print1(a(n), ", "));
Cf. A005014 (variant), A214690.
Sequence in context: A332115 A262655 A075598 * A261822 A105230 A222768
Adjacent sequences: A214688 A214689 A214690 * A214692 A214693 A214694
nonn
Paul D. Hanna, Jul 26 2012
approved
