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

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

1,2

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

Cf. A000203, A095118.

Sequence in context: A156937 A135640 A306854 * A175742 A102793 A144770

Adjacent sequences: A095116 A095117 A095118 * A095120 A095121 A095122

Keyword

nonn

Author

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

Status

approved