G.f. A(x) = exp( Sum_{n>=1} sigma(n)*sigma(2*n) * x^n/n ), where sigma(n) = A000203(n) is the sum of the divisors of n.
A382125
G.f. A(x) = exp( Sum_{n>=1} sigma(n)*sigma(2*n) * x^n/n ), where sigma(n) = A000203(n) is the sum of the divisors of n.
Terms
- a(0) =1a(1) =3a(2) =15a(3) =52a(4) =180a(5) =555a(6) =1696a(7) =4809a(8) =13410a(9) =35844a(10) =93771a(11) =238305a(12) =594403a(13) =1449441a(14) =3476607a(15) =8190824a(16) =19015548a(17) =43492230a(18) =98197506a(19) =218885763a(20) =482337864a(21) =1051051262a(22) =2266904481a(23) =4840955055a(24) =10242621395a(25) =21479302368a(26) =44666897613a(27) =92139573135a(28) =188617118541a(29) =383280793962
External references
- oeis: A382125