a(n) = [x^n] Product_{k=1..n} 1/(1-k^2*x).

A298851

a(n) = [x^n] Product_{k=1..n} 1/(1-k^2*x).

Terms

    a(0) =1a(1) =1a(2) =21a(3) =1408a(4) =196053a(5) =46587905a(6) =16875270660

External references