OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
840 is in the sequence because s(840) = 3070 >= 2880 = sigma(840).
MATHEMATICA
s[n_]:=Plus@@(Select[Divisors[n], #^2<=n&]^2); Select[Range[4000], s[ # ]>=DivisorSigma[1, # ]&]
PROG
(PARI) isok(n) = sumdiv(n, d, if (d^2 <= n, d^2)) >= sigma(n); \\ Michel Marcus, Aug 13 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Dean Hickerson, following a suggestion of Leroy Quet, May 28 2004
STATUS
approved