0,1

a(n) = (1+sqrt(2))^(n^2) + (1-sqrt(2))^(n^2).

Logarithmic derivative of A165937.

(PARI) {a(n)=polcoeff(2*(1-x)/(1-2*x-x^2 +x*O(x^(n^2))), n^2)}

Cf. A165937, A002203, A000129 (Pell numbers).

Sequence in context: A045585 A092883 A134495 this_sequence A002782 A155205 A045529

Adjacent sequences: A165935 A165936 A165937 this_sequence A165939 A165940 A165941

nonn

Paul D. Hanna (pauldhanna(AT)juno.com), Oct 18 2009