a(n) = [x^n] Product_{k=1..n} 1/(1-k^k*x).A299035a(n) = [x^n] Product_{k=1..n} 1/(1-k^k*x).Terms a(0) =1a(1) =1a(2) =21a(3) =23980a(4) =4896624249External referencesoeis: A299035