OFFSET
1,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
FORMULA
Conjecture: for n > 10^6, a(n) < n^2. - Benoit Cloitre, Aug 24 2002
EXAMPLE
x = 75: D[75] = {1, 3, 5, 15, 25, 75}, D[sigma(75)] = D[124] = {1, 2, 4, 31, 62, 124}, both x and sigma[x] have 6 divisors, so 75 is here.
MATHEMATICA
Do[s=DivisorSigma[0, DivisorSigma[1, n]]; s0=DivisorSigma[0, n]; If[Greater[s0, s], Print[n]], {n, 1, 1000}]
PROG
(PARI) is(n)=numdiv(sigma(n))==numdiv(n) \\ Charles R Greathouse IV, Feb 13 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Offset corrected by Reinhard Zumkeller, Jun 18 2009
Name edited by Michel Marcus, Nov 12 2023
STATUS
approved