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 A255265 Numbers representable as x*y*(x+y), where x>=y>1. 4

%I #17 Mar 22 2023 19:38:03

%S 16,30,48,54,70,84,96,120,126,128,160,162,180,198,210,240,250,264,286,

%T 308,324,330,336,384,390,420,432,448,462,468,510,520,540,546,560,576,

%U 624,630,646,660,672,686,714,720,750,768,798,810,840,880,884,912,960,966,1008

%N Numbers representable as x*y*(x+y), where x>=y>1.

%e a(2) = 30 = 3*2*(3+2).

%e a(5) = 70 = 5*2*(5+2).

%t r[n_] := Reduce[x >= y > 1 && n == x*y*(x+y), {x, y}, Integers]; Reap[For[n = 2, n <= 1000, n = n+2, If[r[n] =!= False, Print[n]; Sow[n]]]][[2, 1]] (* _Jean-François Alcover_, Feb 26 2015 *)

%o (Python)

%o TOP = 10000

%o a = [0] * TOP

%o for y in range(2, TOP // 2):

%o for x in range(y, TOP // 2):

%o k = x * y * (x + y)

%o if k >= TOP:

%o break

%o a[k] += 1

%o print([n for n in range(TOP) if a[n] > 0])

%Y Cf. A254671.

%K nonn

%O 1,1

%A _Alex Ratushnyak_, Feb 19 2015

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Last modified September 15 08:55 EDT 2024. Contains 375932 sequences. (Running on oeis4.)