a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(4*n-2*k-3,n-2*k).
A390682
a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(4*n-2*k-3,n-2*k).
Terms
- a(0) =1a(1) =1a(2) =9a(3) =77a(4) =661a(5) =5746a(6) =50523a(7) =448362a(8) =4008533a(9) =36053380a(10) =325870824a(11) =2957523101a(12) =26935038035a(13) =246034329464
External references
- oeis: A390682