A255266 Numbers representable in more than one way as x*y*(x+y), where x>=y>1.

240, 390, 810, 880, 1008, 1020, 1680, 1920, 2100, 2310, 2970, 3120, 3360, 3696, 3750, 4320, 4914, 5460, 5670, 6090, 6270, 6480, 6630, 7040, 7380, 7440, 7770, 8064, 8160, 8190, 8448, 8580, 8976, 9240, 9520, 10290, 10530, 10640, 11340, 11856, 12474, 13440, 13776, 14040

Offset

1,1

Links

Table of n, a(n) for n=1..44.

Example

a(3) = 810 = 15*3*(15+3) = 9*6*(9+6).

Prog

(Python)
TOP = 100000
a = [0]*TOP
for y in range(2, TOP//2):
  for x in range(y, TOP//2):
    k = x*y*(x+y)
    if k>=TOP: break
    a[k]+=1
print([n for n in range(TOP) if a[n]>1])

Crossrefs

Cf. A255265, A081779.

Sequence in context: A179644 A099833 A272950 * A179440 A154378 A300145

Adjacent sequences: A255263 A255264 A255265 * A255267 A255268 A255269

Keyword

nonn

Author

Alex Ratushnyak, Feb 19 2015

Status

approved