OFFSET
1,1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
Aleksandar Ivić, An asymptotic formula involving the enumerating function of finite Abelian groups, Publikacije Elektrotehničkog fakulteta, Serija Matematika 3 (1992), pp. 61-66.
Imre Kátai, On a problem of A. Ivic, Mathematica Pannonica, Vol. 18, No. 1 (2007), pp. 11-18.
FORMULA
Sum_{k=1..n} a(k) ~ D*n*log(n) + O(n*log(n)/log(log(n))), where D > 0 is a constant (conjectured with an error O(n) by Ivić, 1992; proven by Kátai, 2007). - Amiram Eldar, Jul 08 2020
MATHEMATICA
Table[DivisorSigma[0, n + DivisorSigma[0, n]], {n, 117}] (* Michael De Vlieger, May 21 2017 *)
PROG
(PARI) A286529(n) = numdiv(n+numdiv(n));
(Python)
from sympy import divisor_count as d
def a(n): return d(n + d(n)) # Indranil Ghosh, May 21 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 21 2017
STATUS
approved