a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(4*n-2*k-1,n-2*k).
A371815
a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(4*n-2*k-1,n-2*k).
Terms
- a(0) =1a(1) =3a(2) =20a(3) =156a(4) =1288a(5) =10963a(6) =95132a(7) =836650a(8) =7430956a(9) =66501696a(10) =598720080a(11) =5416612336a(12) =49201807276a(13) =448442474938
External references
- oeis: A371815