0,2

The full set of integer solutions to this equation consists of the pairs [X(i),Y(i)] = [1+-A001081(i), Y(i)=A001080(i)]. The present generates every second one of them: a(n) = [A001081(2n)-1]/2. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 20 2007

a(0)=0, a(1)=63 and a(n)=254*a(n-1) - a(n-2) + 126.

G.f.: -63*x*(1+x)/(-1+x)/(1-254*x+x^2). a(n) = [A001081(2n)-1]/2. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 20 2007

a(n)=-(1/2)+(1/4)*[127-48*sqrt(7)]^n+(1/4)*[127+48*sqrt(7)]^n, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Sep 26 2008]

Cf. A007654.

Cf. A001080, A001081.

Sequence in context: A093263 A069433 A104179 this_sequence A001238 A110852 A136677

Adjacent sequences: A132591 A132592 A132593 this_sequence A132595 A132596 A132597

nonn

Mohamed Bouhamida (bhmd95(AT)yahoo.fr), Nov 14 2007