a(0) = 1; for n >= 1, a(n) = A000040(n) * A002110(n).

A286630

a(0) = 1; for n >= 1, a(n) = A000040(n) * A002110(n).

Terms

    a(0) =1a(1) =4a(2) =18a(3) =150a(4) =1470a(5) =25410a(6) =390390a(7) =8678670a(8) =184294110a(9) =5131136010a(10) =187621103670

External references