a(n) = product(i >= 0, P(n, i)^(2^i)) where P(n, i) = product(p prime, n/2^(i+1) < p <= n/2^i).

A220027

a(n) = product(i >= 0, P(n, i)^(2^i)) where P(n, i) = product(p prime, n/2^(i+1) < p <= n/2^i).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =12a(5) =60a(6) =180a(7) =1260a(8) =5040a(9) =5040a(10) =25200a(11) =277200a(12) =2494800a(13) =32432400a(14) =227026800a(15) =227026800a(16) =3632428800a(17) =61751289600a(18) =61751289600

External references