Integers of the form Product p_j^k_j = Product k_j^p_j; p_j in A000040.

Terms

a(0) =1a(1) =4a(2) =16a(3) =27a(4) =72a(5) =108a(6) =432a(7) =800a(8) =3125a(9) =6272a(10) =12500a(11) =21600a(12) =30375a(13) =50000a(14) =84375a(15) =121500a(16) =169344a(17) =225000a(18) =247808a(19) =337500a(20) =486000a(21) =750141a(22) =823543a(23) =1350000a(24) =1384448a(25) =3000564a(26) =3294172a(27) =6690816a(28) =12002256a(29) =13176688