G.f. satisfies: A(x) = exp( Sum_{n>=1} [Sum_{k=0..2*n} T(n,k)^2 * x^k] / A(x)^n * x^n/n ), where T(n,k) is the coefficient of x^k in (1+2*x)^n*(1+3*x)^n.
A251688
G.f. satisfies: A(x) = exp( Sum_{n>=1} [Sum_{k=0..2*n} T(n,k)^2 * x^k] / A(x)^n * x^n/n ), where T(n,k) is the coefficient of x^k in (1+2*x)^n*(1+3*x)^n.
Terms
- a(0) =1a(1) =1a(2) =25a(3) =61a(4) =336a(5) =1200a(6) =3600a(7) =13500a(8) =32400a(9) =118800a(10) =259200a(11) =939600a(12) =1944000a(13) =6998400a(14) =13996800a(15) =50155200a(16) =97977600a(17) =349920000a(18) =671846400a(19) =2393452800a(20) =4534963200a(21) =16124313600a(22) =30233088000a(23) =107327462400a(24) =199538380800a(25) =707454259200
External references
- oeis: A251688