G.f. A(x) satisfies: coefficient of x^n in A(x)^(2*n) equals A000172(n) = Sum_{k=0..n} C(n,k)^3, the n-th Franel number.
A242903
G.f. A(x) satisfies: coefficient of x^n in A(x)^(2*n) equals A000172(n) = Sum_{k=0..n} C(n,k)^3, the n-th Franel number.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =8a(6) =26a(7) =89a(8) =324a(9) =1225a(10) =4786a(11) =19170a(12) =78408a(13) =326275a(14) =1377772a(15) =5891401a(16) =25467509a(17) =111144579a(18) =489145720a(19) =2168854885a(20) =9681072845a(21) =43473716527a(22) =196286934526a(23) =890640262188
External references
- oeis: A242903