A056761 Odd numbers less than the cube of their number of divisors.

3, 5, 7, 9, 15, 21, 25, 27, 33, 35, 39, 45, 51, 55, 57, 63, 75, 81, 99, 105, 117, 135, 147, 153, 165, 171, 175, 189, 195, 207, 225, 231, 255, 273, 285, 297, 315, 345, 351, 357, 375, 385, 399, 405, 429, 435, 441, 455, 459, 465, 483, 495, 525, 567, 585, 675, 693

Offset

1,1

Comments

Last term is a(267) = 883575, confirming the author's conjecture. - Charles R Greathouse IV, Apr 27 2011

Links

Zak Seidov, Table of n, a(n) for n = 1..267 (complete sequence)

Example

14175 = 81*25*7 has 30 divisors, and 30^3 = 27000 > 14175.

Mathematica

Select[Range[1, 10^6 + 1, 2], DivisorSigma[0, #]^3 > # &] (* Michael De Vlieger, Oct 26 2017 *)

Prog

(PARI) isok(n) = (n % 2) && (numdiv(n)^3 > n); \\ Michel Marcus, Dec 19 2013

Crossrefs

Cf. A035033-A035035, A034884, A000005, A000265, A056757-A056767, A056781.

Sequence in context: A109790 A290426 A211137 * A108347 A211128 A211129

Adjacent sequences: A056758 A056759 A056760 * A056762 A056763 A056764

Keyword

fini,full,nonn

Author

Labos Elemer, Aug 16 2000

Status

approved