a(n) = binomial(sigma(n),tau(n)), where sigma(n) is the sum and tau(n) the number of divisors of n (A000203, A000005).

A068904

a(n) = binomial(sigma(n),tau(n)), where sigma(n) is the sum and tau(n) the number of divisors of n (A000203, A000005).

Terms

    a(0) =1a(1) =3a(2) =6a(3) =35a(4) =15a(5) =495a(6) =28a(7) =1365a(8) =286a(9) =3060a(10) =66a(11) =376740a(12) =91a(13) =10626a(14) =10626a(15) =169911a(16) =153a(17) =3262623a(18) =190a(19) =5245786a(20) =35960a(21) =58905a(22) =276a(23) =2558620845a(24) =4495a(25) =111930a(26) =91390a(27) =32468436a(28) =435a(29) =11969016345

External references