a(n) = [x^n] 1/(1 - x)^(n*(n+1)/2).
A386880
a(n) = [x^n] 1/(1 - x)^(n*(n+1)/2).
Terms
- a(0) =1a(1) =1a(2) =6a(3) =56a(4) =715a(5) =11628a(6) =230230a(7) =5379616a(8) =145008513a(9) =4431613550a(10) =151473214816
External references
- oeis: A386880
A386880
a(n) = [x^n] 1/(1 - x)^(n*(n+1)/2).