A267893 Numbers with 10 odd divisors.

405, 567, 810, 891, 1053, 1134, 1377, 1539, 1620, 1782, 1863, 1875, 2106, 2268, 2349, 2511, 2754, 2997, 3078, 3240, 3321, 3483, 3564, 3726, 3750, 3807, 4212, 4293, 4375, 4536, 4698, 4779, 4941, 5022, 5427, 5508, 5751, 5913, 5994, 6156, 6399, 6480, 6642, 6723, 6875, 6966, 7128, 7203, 7209, 7452, 7500, 7614, 7857, 8125

Offset

1,1

Comments

Positive integers that have exactly 10 odd divisors.

Numbers n such that the symmetric representation of sigma(n) has 10 subparts. - Omar E. Pol, Dec 29 2016

Numbers that can be formed in exactly 9 ways by summing sequences of 2 or more consecutive positive integers. - Julie Jones, Aug 13 2018

Links

Muniru A Asiru, Table of n, a(n) for n = 1..5000

Formula

A001227(a(n)) = 10.

Mathematica

Select[Range@ 8125, Length@ Select[Divisors@ #, OddQ] == 10 &] (* Michael De Vlieger, Dec 30 2016 *)

Prog

(PARI) isok(n) = sumdiv(n, d, (d%2)) == 10; \\ after Michel Marcus
(GAP) A:=List([1..10000], n->DivisorsInt(n));; B:=List([1..Length(A)], i->Filtered(A[i], IsOddInt));;
a:=Filtered([1..Length(B)], i->Length(B[i])=10); # Muniru A Asiru, Aug 14 2018

Crossrefs

Column 10 of A266531.

Cf. A001227, A038547, A237593, A279387.

Numbers with exactly k odd divisors (k = 1..10): A000079, A038550, A072502, apparently A131651, A267696, A230577, A267697, A267891, A267892, this sequence.

Sequence in context: A198536 A337047 A169904 * A151745 A204636 A224527

Adjacent sequences: A267890 A267891 A267892 * A267894 A267895 A267896

Keyword

nonn

Author

Omar E. Pol, Apr 03 2016

Status

approved