G.f.: exp( Sum_{n>=1} sigma_2(n)*sigma_3(n)/sigma(n) * x^n / n ), where sigma_{k}(n) equals the sum of the k-th powers of the divisors of n.
A320416
G.f.: exp( Sum_{n>=1} sigma_2(n)*sigma_3(n)/sigma(n) * x^n / n ), where sigma_{k}(n) equals the sum of the k-th powers of the divisors of n.
Terms
- a(0) =1a(1) =1a(2) =8a(3) =31a(4) =110a(5) =380a(6) =1258a(7) =4145a(8) =13062a(9) =40549a(10) =123177a(11) =367524a(12) =1078214a(13) =3117641a(14) =8889005a(15) =25019907a(16) =69592393a(17) =191419803a(18) =521053616a(19) =1404437257a(20) =3750615009a(21) =9928671171a(22) =26065603448a(23) =67890853023a(24) =175503159857a(25) =450440887668
External references
- oeis: A320416