A095119 Numbers k such that s(k) >= sigma(k), where s(k) = A095118(k) is the sum of the squares of the divisors of k which are <= sqrt(k) and sigma(k) = A000203(k) is the sum of the divisors of k.

1, 840, 900, 1080, 1225, 1260, 1440, 1600, 1680, 1800, 1848, 1890, 1980, 2016, 2100, 2160, 2340, 2400, 2520, 2640, 2700, 2772, 2800, 2880, 2970, 3024, 3080, 3120, 3136, 3150, 3240, 3276, 3300, 3360, 3465, 3528, 3600, 3640, 3696, 3780, 3900, 3960, 3969

Offset: 1

Author

Dean Hickerson, following a suggestion of Leroy Quet, May 28 2004

Keywords

• nonn

Examples

			840 is in the sequence because s(840) = 3070 >= 2880 = sigma(840).
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203, A095118.

Programs

Mathematica

s[n_]:=Plus@@(Select[Divisors[n], #^2<=n&]^2); Select[Range[4000], s[ # ]>=DivisorSigma[1, # ]&]

PARI

isok(n) = sumdiv(n, d, if (d^2 <= n, d^2)) >= sigma(n); \\ Michel Marcus, Aug 13 2019