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A056761 Odd numbers less than the cube of their number of divisors. 3

%I #26 Jun 20 2021 07:35:39

%S 3,5,7,9,15,21,25,27,33,35,39,45,51,55,57,63,75,81,99,105,117,135,147,

%T 153,165,171,175,189,195,207,225,231,255,273,285,297,315,345,351,357,

%U 375,385,399,405,429,435,441,455,459,465,483,495,525,567,585,675,693

%N Odd numbers less than the cube of their number of divisors.

%C Last term is a(267) = 883575, confirming the author's conjecture. - _Charles R Greathouse IV_, Apr 27 2011

%H Zak Seidov, <a href="/A056761/b056761.txt">Table of n, a(n) for n = 1..267</a> (complete sequence)

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

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

%o (PARI) isok(n) = (n % 2) && (numdiv(n)^3 > n); \\ _Michel Marcus_, Dec 19 2013

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

%K fini,full,nonn

%O 1,1

%A _Labos Elemer_, Aug 16 2000

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Last modified April 19 16:52 EDT 2024. Contains 371794 sequences. (Running on oeis4.)