OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: (1/x)*(Sum_{k>=1} k^2*x^k/(1 - x^k))^2. - Ilya Gutkovskiy, Jan 01 2017
MAPLE
with(numtheory): T:=array(1..200):for p from 1 to 200 do: liste:=divisors(p) :s2:=sum(liste[i]^2, i=1..nops(liste)):T[p] :=s2 :od : for n from 1 to 100 do: printf(`%d, `, sum (T[k]*T[n+1-k], k=1..n)):od:
MATHEMATICA
a[n_] := Sum[DivisorSigma[2, k] * DivisorSigma[2, n + 1 - k], {k, 1, n}]; Array[a, 34] (* Amiram Eldar, Jul 31 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Aug 10 2010
EXTENSIONS
Definition slightly rephrased by R. J. Mathar, Aug 19 2010
STATUS
approved