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A230577 Positive integers that have exactly 6 odd divisors. 8

%I #22 Dec 29 2016 05:19:42

%S 45,63,75,90,99,117,126,147,150,153,171,175,180,198,207,234,243,245,

%T 252,261,275,279,294,300,306,325,333,342,350,360,363,369,387,396,414,

%U 423,425,468,475,477,486,490

%N Positive integers that have exactly 6 odd divisors.

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

%C Column 6 of A266531. - _Omar E. Pol_, Apr 03 2016

%C Numbers n such that the symmetric representation of sigma(n) has 6 subparts. - _Omar E. Pol_, Dec 28 2016

%H Charles R Greathouse IV, <a href="/A230577/b230577.txt">Table of n, a(n) for n = 1..10000</a>

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

%o (PARI) is(n)=numdiv(n>>valuation(n,2))==6 \\ _Charles R Greathouse IV_, Oct 28 2013

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

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

%K nonn

%O 1,1

%A _Philippe Beaudoin_, Oct 23 2013

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Last modified April 25 05:18 EDT 2024. Contains 371964 sequences. (Running on oeis4.)