a(n) = T(n,1) + T(n,n), where T(n,k) is A391880.
A391881
a(n) = T(n,1) + T(n,n), where T(n,k) is A391880.
Terms
- a(0) =4a(1) =5a(2) =10a(3) =18a(4) =37462a(5) =24a(6) =1367566a(7) =60a(8) =196607854a(9) =60a(10) =120670499918a(11) =330a(13) =16043622a(15) =2142130380a(17) =3227805300
External references
- oeis: A391881