a(0)=-1, a(1)=1; a(n) = n*a(n-1) + (n-2)*a(n-2) + Sum_{j=1..n-1} a(j)*a(n-j) + 2*Sum_{j=0..n-1} a(j)*a(n-1-j).
A259872
a(0)=-1, a(1)=1; a(n) = n*a(n-1) + (n-2)*a(n-2) + Sum_{j=1..n-1} a(j)*a(n-j) + 2*Sum_{j=0..n-1} a(j)*a(n-1-j).
Terms
- a(0) =-1a(1) =1a(2) =-1a(3) =2a(4) =-1a(5) =9a(6) =26a(7) =201a(8) =1407a(9) =11714a(10) =107983a(11) =1102433a(12) =12332994a(13) =150103585a(14) =1974901951a(15) =27935229074a(16) =422799610943
External references
- oeis: A259872