G.f.: 1 / AGM(1-21*x, sqrt((1-9*x)*(1-49*x))).

A246906

G.f.: 1 / AGM(1-21*x, sqrt((1-9*x)*(1-49*x))).

Terms

    a(0) =1a(1) =25a(2) =729a(3) =24025a(4) =866761a(5) =33350625a(6) =1342856025a(7) =55849505625

External references