A025412 Numbers that are the sum of 4 distinct positive cubes in 2 or more ways.

1036, 1134, 1352, 1367, 1430, 1465, 1484, 1521, 1547, 1582, 1638, 1709, 1736, 1764, 1800, 1801, 1820, 1862, 1863, 1881, 1918, 1953, 1972, 2009, 2070, 2080, 2099, 2136, 2197, 2249, 2268, 2288, 2305, 2331, 2340, 2366, 2422, 2457, 2464, 2483, 2485, 2520

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

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

Crossrefs

Cf. A025409, A025421.

Programs

Maple

M:= 4000: # for terms <= M
V:= Vector(M):
for a from 1 while 4*a^3 < M do
  for b from a+1 while a^3 + 3*b^3 < M do
    for c from b+1 while a^3 + b^3 + 2*c^3 < M do
      for d from c+1 do
        v:= a^3 + b^3 + c^3 + d^3;
        if v > M then break fi;
        V[v]:= V[v]+1
od od od od:
select(t -> V[t] > 1, [$1..M]); # Robert Israel, Oct 23 2023