A230577 Positive integers that have exactly 6 odd divisors.

45, 63, 75, 90, 99, 117, 126, 147, 150, 153, 171, 175, 180, 198, 207, 234, 243, 245, 252, 261, 275, 279, 294, 300, 306, 325, 333, 342, 350, 360, 363, 369, 387, 396, 414, 423, 425, 468, 475, 477, 486, 490

Offset: 1

Author

Philippe Beaudoin, Oct 23 2013

Keywords

• nonn

Comments

Numbers that can be formed in exactly 5 ways by summing sequences of 2 or more consecutive integers.

Column 6 of A266531. - Omar E. Pol, Apr 03 2016

Numbers n such that the symmetric representation of sigma(n) has 6 subparts. - Omar E. Pol, Dec 28 2016

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000203, A001227, A077646, A237593, A279387, A266531.

Numbers with k odd divisors (k = 1..10): A000079, A038550, A072502, apparently A131651, A267696, this sequence, A267697, A267891, A267892, A267893.

Programs

Mathematica

Select[Range[500],Count[Divisors[#],?OddQ]==6&] (* _Harvey P. Dale, Mar 25 2015 *)

PARI

is(n)=numdiv(n>>valuation(n,2))==6 \\ Charles R Greathouse IV, Oct 28 2013