a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026681.
A026987
a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026681.
Terms
- a(0) =1a(1) =6a(2) =35a(3) =154a(4) =613a(5) =2882a(6) =14995a(7) =68730a(8) =291606a(9) =1378110a(10) =7047087a(11) =32801046a(12) =143237183a(13) =681449778a(14) =3462931356a(15) =16261134650a(16) =72210836920a(17) =345094694354
External references
- oeis: A026987