a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026780.
A027249
a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026780.
Terms
- a(0) =1a(1) =9a(2) =59a(3) =338a(4) =1937a(5) =10289a(6) =57345a(7) =299832a(8) =1663421a(9) =8705069a(10) =48391863a(11) =254818488a(12) =1421911953a(13) =7544528179a(14) =42264280735a(15) =225949128338
External references
- oeis: A027249