a(n) = Sum_{k=0..n} (-1)^k * binomial(2*n+k-1,k) * binomial(4*n-k-1,n-k).

A370103

a(n) = Sum_{k=0..n} (-1)^k * binomial(2*n+k-1,k) * binomial(4*n-k-1,n-k).

Terms

    a(0) =1a(1) =1a(2) =7a(3) =28a(4) =151a(5) =751a(6) =3976a(7) =20924a(8) =112023a(9) =602182a(10) =3260257a(11) =17724928a(12) =96766072a(13) =529977917a(14) =2910984412a(15) =16027963528a(16) =88440034711a(17) =488918693466

External references