A025398 - OEIS

%I #29 Aug 05 2021 15:29:00

%S 5104,9729,12104,12221,12384,13896,14175,17604,17928,19034,20691,

%T 21412,21888,24480,28792,29457,30528,31221,32850,34497,35216,36288,

%U 38259,39339,39376,40041,40060,40097,40832,40851,41033,41040,41364,41966,42056,42687

%N Numbers that are the sum of 3 positive cubes in 3 or more ways.

%H Donovan Johnson, <a href="/A025398/b025398.txt">Table of n, a(n) for n = 1..10000</a>

%F A008917(n) < a(n) <= A025397(n). - _Jonathan Sondow_, Oct 24 2013

%F {n: A025456(n) >= 3}. - _R. J. Mathar_, Jun 15 2018

%e a(1) = A230477(3) = 5104 = 1^3 + 12^3 + 15^3 = 2^3 + 10^3 + 16^3 = 9^3 + 10^3 + 15^3. - _Jonathan Sondow_, Oct 24 2013

%t Select[ Range[ 50000], 2 < Length @ Cases[ PowersRepresentations[#, 3, 3], {_?Positive, _?Positive, _?Positive}] &] (* adapted from Alcover's program for A008917 by _Jonathan Sondow_, Oct 24 2013 *)

%o (PARI) is(n)=k=ceil((n-2)^(1/3)); d=0; for(a=1,k,for(b=a,k,for(c=b,k,if(a^3+b^3+c^3==n,d++))));d

%o n=3;while(n<50000,if(is(n)>=3,print1(n,", "));n++) \\ _Derek Orr_, Aug 27 2015

%Y Cf. A008917, A018787, A025331, A025397, A025402, A025407, A230477, A343968, A344239.

%K nonn

%O 1,1

%A _David W. Wilson_