a(n) = Pell(n)*A028594(n) for n>=1, with a(0)=1, where A028594 lists the coefficients in (theta_3(x)*theta_3(7*x)+theta_2(x)*theta_2(7*x))^2.

A209456

a(n) = Pell(n)*A028594(n) for n>=1, with a(0)=1, where A028594 lists the coefficients in (theta_3(x)*theta_3(7*x)+theta_2(x)*theta_2(7*x))^2.

Terms

    a(0) =1a(1) =4a(2) =24a(3) =80a(4) =336a(5) =696a(6) =3360a(7) =676a(8) =24480a(9) =51220a(10) =171216a(11) =275568a(12) =1552320a(13) =1873816a(14) =969384a(15) =18722400a(16) =58383168a(17) =81841608a(18) =428096760a(19) =530008720a(20) =2687063904a(21) =617823440a(22) =13424019552a(23) =21605633376a(24) =130401532800a(25) =162655527004a(26) =532025081616

External references