a(n) = Sum_{k=0..floor(n/4)} (5*k+1) * binomial(3*n-7*k+1,n-4*k)/(3*n-7*k+1).
A390486
a(n) = Sum_{k=0..floor(n/4)} (5*k+1) * binomial(3*n-7*k+1,n-4*k)/(3*n-7*k+1).
Terms
- a(0) =1a(1) =1a(2) =3a(3) =12a(4) =56a(5) =279a(6) =1461a(7) =7934a(8) =44284a(9) =252500a(10) =1464452a(11) =8612607a(12) =51241929a(13) =307870618a(14) =1865311344a(15) =11383768925a(16) =69915894616a(17) =431811981838
External references
- oeis: A390486