cp's OEIS Frontend

A025406 Numbers that are the sum of 4 positive cubes in 2 or more ways.

%I A025406 #19 Aug 05 2021 15:27:04
%S A025406 219,252,259,278,315,376,467,522,594,702,758,763,765,802,809,819,856,
%T A025406 864,945,980,1010,1017,1036,1043,1073,1078,1081,1118,1134,1160,1225,
%U A025406 1251,1352,1367,1368,1374,1375,1393,1397,1423,1430,1458,1460,1465,1467,1484
%N A025406 Numbers that are the sum of 4 positive cubes in 2 or more ways.
%H A025406 Robert Israel, <a href="/A025406/b025406.txt">Table of n, a(n) for n = 1..10000</a>
%F A025406 {n: A025457(n) >= 2}. - _R. J. Mathar_, Jun 15 2018
%p A025406 N:= 2000: # for terms <= N
%p A025406 S2:= {}: S1:= {}:
%p A025406 for x from 1 while x^3 < N do
%p A025406 for y from 1 to x while x^3 + y^3 < N do
%p A025406   for z from 1 to y while x^3 + y^3 + z^3 < N do
%p A025406     for w from 1 to z do
%p A025406     v:= x^3 + y^3 + z^3 + w^3;
%p A025406     if v > N then break fi;
%p A025406     if member(v,S1) then S2:= S2 union {v}
%p A025406     else S1:= S1 union {v}
%p A025406     fi
%p A025406 od od od od:
%p A025406 sort(convert(S2,list)); # _Robert Israel_, Feb 24 2021
%Y A025406 Cf. A003327, A008917, A025367, A025404, A025407, A025457, A309763, A343702.
%K A025406 nonn
%O A025406 1,1
%A A025406 _David W. Wilson_