|
|
A308570
|
|
a(n) = sigma_{2*n}(n).
|
|
4
|
|
|
1, 17, 730, 65793, 9765626, 2177317874, 678223072850, 281479271743489, 150094635684419611, 100000095367432689202, 81402749386839761113322, 79496851942053939878082786, 91733330193268616658399616010, 123476696151234472370970011268514
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
L.g.f.: -log(Product_{k>=1} (1 - (k^2*x)^k)^(1/k)) = Sum_{k>=1} a(k)*x^k/k.
|
|
MATHEMATICA
|
|
|
PROG
|
(PARI) {a(n) = sigma(n, 2*n)}
(PARI) N=20; x='x+O('x^N); Vec(x*deriv(-log(prod(k=1, N, (1-(k^2*x)^k)^(1/k)))))
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|