A371721 Numbers representable in the form u*v*(u+v) for u >= v >= 0 in at least two ways.

0, 30, 210, 240, 390, 420, 462, 810, 880, 1008, 1020, 1056, 1122, 1190, 1482, 1680, 1920, 1980, 2070, 2100, 2310, 2970, 3120, 3360, 3696, 3750, 4160, 4290, 4320, 4830, 4914, 5460, 5670, 6006, 6090, 6270, 6480, 6630, 7040, 7380, 7440, 7770, 8064, 8160, 8190, 8448, 8580, 8976, 9120, 9240, 9520, 9900, 10290, 10530, 10640, 11340, 11856, 12210, 12432, 12474, 13110

Offset: 1

Author

Max Alekseyev, Apr 04 2024

Keywords

• nonn

Links

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

Crossrefs

Subsequence of A088915.

Cf. A369333, A369334.

Programs

Maple

N:= 10^5: # for terms <= N
V:= Vector(N):
for v from 1 while 2*v^3 <= N do
  for u from v do
    x:= u*v*(u+v);
    if x > N then break fi;
    V[x]:= V[x]+1
od od:
[0,op(select(t -> V[t] >= 2, [$1..N]))]; # Robert Israel, Dec 15 2024