

A055720


Numbers k such that d(k)+1  k.


1



3, 4, 10, 15, 28, 35, 54, 55, 63, 64, 65, 85, 95, 98, 100, 115, 125, 135, 144, 145, 147, 155, 156, 175, 176, 185, 189, 205, 215, 234, 235, 245, 260, 265, 295, 297, 305, 335, 336, 351, 355, 364, 365, 395, 400, 408, 415, 416, 445, 459, 485
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OFFSET

1,1


COMMENTS

Integers divisible by 1 more than the number of their divisors. The only prime is 3.
These numbers cannot be very orderly numbers (A167409).  T. D. Noe, Nov 13 2009


LINKS

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


MATHEMATICA

Select[Range[1000], Mod[ #, 1 + DivisorSigma[0, # ]] == 0 &]


PROG

(PARI) isok(k) = Mod(k, numdiv(k)+1) == 0; \\ Michel Marcus, Mar 12 2020


CROSSREFS

Cf. A000005, A167409.
Sequence in context: A204292 A218277 A103080 * A054184 A307057 A188022
Adjacent sequences: A055717 A055718 A055719 * A055721 A055722 A055723


KEYWORD

nonn


AUTHOR

Robert G. Wilson v, Jun 09 2000


EXTENSIONS

Edited by T. D. Noe, Nov 13 2009


STATUS

approved



