a(n) = 0^n + 2((n+1)^n - (-1)^n) / (n+2).
A091759
a(n) = 0^n + 2((n+1)^n - (-1)^n) / (n+2).
Terms
- a(0) =1a(1) =2a(2) =4a(3) =26a(4) =208a(5) =2222a(6) =29412a(7) =466034a(8) =8609344a(9) =181818182a(10) =4322904100a(11) =114308980106
External references
- oeis: A091759