A025406 - OEIS

%I #19 Aug 05 2021 15:27:04

%S 219,252,259,278,315,376,467,522,594,702,758,763,765,802,809,819,856,

%T 864,945,980,1010,1017,1036,1043,1073,1078,1081,1118,1134,1160,1225,

%U 1251,1352,1367,1368,1374,1375,1393,1397,1423,1430,1458,1460,1465,1467,1484

%N Numbers that are the sum of 4 positive cubes in 2 or more ways.

%H Robert Israel, <a href="/A025406/b025406.txt">Table of n, a(n) for n = 1..10000</a>

%F {n: A025457(n) >= 2}. - _R. J. Mathar_, Jun 15 2018

%p N:= 2000: # for terms <= N

%p S2:= {}: S1:= {}:

%p for x from 1 while x^3 < N do

%p for y from 1 to x while x^3 + y^3 < N do

%p   for z from 1 to y while x^3 + y^3 + z^3 < N do

%p     for w from 1 to z do

%p     v:= x^3 + y^3 + z^3 + w^3;

%p     if v > N then break fi;

%p     if member(v,S1) then S2:= S2 union {v}

%p     else S1:= S1 union {v}

%p     fi

%p od od od od:

%p sort(convert(S2,list)); # _Robert Israel_, Feb 24 2021

%Y Cf. A003327, A008917, A025367, A025404, A025407, A025457, A309763, A343702.

%K nonn

%O 1,1

%A _David W. Wilson_