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

219, 252, 259, 278, 315, 376, 467, 522, 594, 702, 758, 763, 765, 802, 809, 819, 856, 864, 945, 980, 1010, 1017, 1036, 1043, 1073, 1078, 1081, 1118, 1134, 1160, 1225, 1251, 1352, 1367, 1368, 1374, 1375, 1393, 1397, 1423, 1430, 1458, 1460, 1465, 1467, 1484

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

{n: A025457(n) >= 2}. - R. J. Mathar, Jun 15 2018

Maple

N:= 2000: # for terms <= N
S2:= {}: S1:= {}:
for x from 1 while x^3 < N do
for y from 1 to x while x^3 + y^3 < N do
  for z from 1 to y while x^3 + y^3 + z^3 < N do
    for w from 1 to z do
    v:= x^3 + y^3 + z^3 + w^3;
    if v > N then break fi;
    if member(v, S1) then S2:= S2 union {v}
    else S1:= S1 union {v}
    fi
od od od od:
sort(convert(S2, list)); # Robert Israel, Feb 24 2021

Crossrefs

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

Sequence in context: A252997 A126829 A171406 * A025404 A361343 A192086

Adjacent sequences: A025403 A025404 A025405 * A025407 A025408 A025409

Keyword

nonn

Author

David W. Wilson

Status

approved