a(n) = [x^n] (1 + x*(1+x)^(n-1) )^(n+1).
A121676
a(n) = [x^n] (1 + x*(1+x)^(n-1) )^(n+1).
Terms
- a(0) =1a(1) =2a(2) =6a(3) =32a(4) =250a(5) =2412a(6) =27524a(7) =360600a(8) =5296050a(9) =85805420a(10) =1515794467a(11) =28926900312a(12) =591903009295
External references
- oeis: A121676