0,2

G.f.: 2/(1-2x+sqrt(1-4x+4x^3)). G.f. satisfies x^2(1-x)A(x)^2-(1-2x)A(x)+1=0.

(PARI) a(n)=polcoeff(2/(1-2*x+sqrt(1-4*x+4*x^3+x*O(x^n))), n)

First backwards difference is A056010.

Sequence in context: A099164 A036765 A136751 this_sequence A125094 A114465 A135310

Adjacent sequences: A087623 A087624 A087625 this_sequence A087627 A087628 A087629

nonn

Michael Somos, Sep 16 2003