OFFSET
1,1
COMMENTS
Logarithmic derivative of A262008.
FORMULA
EXAMPLE
L.g.f.: L(x) = 2*x + 24*x^2/2 + 530*x^3/3 + 65632*x^4/4 + 33554482*x^5/5 + 68719479000*x^6/6 + 562949953421410*x^7/7 + ...
where
exp(L(x)) = 1 + 2*x + 14*x^2 + 202*x^3 + 16858*x^4 + 6746346*x^5 + 11466918526*x^6 + ... + A262008(n)*x^n + ...
MATHEMATICA
a[n_] := DivisorSum[n, 2^(#^2) * (n/#)^2 &]; Array[a, 13] (* Amiram Eldar, Aug 24 2023 *)
PROG
(PARI) {a(n) = sumdiv(n, d, 2^(d^2) * n^2/d^2)}
for(n=1, 20, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 01 2015
STATUS
approved