d_4(n), or tau_4(n), the number of ordered factorizations of n as n = rstu.

Terms

a(0) =1a(1) =4a(2) =4a(3) =10a(4) =4a(5) =16a(6) =4a(7) =20a(8) =10a(9) =16a(10) =4a(11) =40a(12) =4a(13) =16a(14) =16a(15) =35a(16) =4a(17) =40a(18) =4a(19) =40a(20) =16a(21) =16a(22) =4a(23) =80a(24) =10a(25) =16a(26) =20a(27) =40a(28) =4a(29) =64