a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026692.
A026993
a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026692.
Terms
- a(0) =1a(1) =6a(2) =32a(3) =180a(4) =984a(5) =4606a(6) =22689a(7) =114992a(8) =567129a(9) =2576582a(10) =12586319a(11) =63131004a(12) =305635176a(13) =1384074886a(14) =6739962365a(15) =33708050180a(16) =162468169385a(17) =737652413014
External references
- oeis: A026993