OFFSET
1,2
REFERENCES
H. J. S. Smith, Report on the Theory of Numbers, reprinted in Vol. 1 of his Collected Math. Papers, Chelsea, NY, 1979, see p. 322.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
G.f.: sum(n>=1, n*x^(n^2)*(1+x^n)/(1-x^n) ). [Joerg Arndt, Jan 30 2011]
a(n) = Sum_{d|n} min(d, n/d). - Seiichi Manyama, Dec 27 2017
MATHEMATICA
Table[Total[Min[#, n/#]&/@Divisors[n]], {n, 90}] (* Harvey P. Dale, Jan 01 2020 *)
PROG
(PARI) {a(n) = sumdiv(n, d, min(d, n/d))} \\ Seiichi Manyama, Dec 27 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 15 2006
STATUS
approved