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A265713 Numbers k such that floor(Sum_{d|k} 1 / sigma(d)) = 3. 9
110880, 166320, 221760, 277200, 327600, 332640, 360360, 388080, 393120, 415800, 443520, 471240, 480480, 491400, 498960, 526680, 540540, 554400, 556920, 582120, 589680, 600600, 622440, 637560, 655200, 665280, 693000, 720720, 776160, 786240, 803880, 831600 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers k such that A265710(k) = floor(A265708(k) / A069934(k)) = floor(A265709(k) / A265710(k)) = 3.

See A265714(n) = the smallest number k such that floor(Sum_{d|k} 1/sigma(d)) = n.

LINKS

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

EXAMPLE

110880 is a term because floor(Sum_{d|110880} 1/sigma(d)) = floor(22333/7440) = 3.

MATHEMATICA

Select[Range[10^5, 9*10^5], Floor[Sum[1/DivisorSigma[1, d], {d, Divisors@ #}]] == 3 &] (* Michael De Vlieger, Dec 31 2015 *)

PROG

(MAGMA) [n: n in [1..1000000] | Floor(&+[1/SumOfDivisors(d): d in Divisors(n)]) eq 3]

(PARI) isok(n) = floor(sumdiv(n, d, 1/sigma(d))) == 3; \\ Michel Marcus, Dec 27 2015

CROSSREFS

Cf. A069934, A000203, A265708, A265709, A265710, A265711, A265712, A265714, A266227, A266228.

Sequence in context: A251191 A206540 A251034 * A114684 A146888 A175535

Adjacent sequences:  A265710 A265711 A265712 * A265714 A265715 A265716

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Dec 25 2015

STATUS

approved

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Last modified May 8 19:28 EDT 2021. Contains 343666 sequences. (Running on oeis4.)