a(n) = Sum_{k=0..n-3} T(n,k) * T(n,k+3), with T given by A026780.
A027250
a(n) = Sum_{k=0..n-3} T(n,k) * T(n,k+3), with T given by A026780.
Terms
- a(0) =1a(1) =12a(2) =95a(3) =639a(4) =3917a(5) =23377a(6) =132553a(7) =762434a(8) =4201955a(9) =23901906a(10) =130453555a(11) =740755012a(12) =4035754137a(13) =22952934073a(14) =125259143235a(15) =714206660342
External references
- oeis: A027250