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 A053990 Numbers of the form x*(x + 1)*y*(y + 1) ("bipronics") where x and y are distinct. 4
 0, 12, 24, 40, 60, 72, 84, 112, 120, 144, 180, 220, 240, 252, 264, 312, 336, 360, 364, 420, 432, 480, 504, 540, 544, 600, 612, 660, 672, 684, 760, 792, 840, 864, 924, 936, 1012, 1080, 1092, 1104, 1120, 1200, 1260, 1300, 1320, 1404, 1440, 1512, 1584, 1624 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE Taking x=1, y=2 gives 2 * 6 =12 MATHEMATICA bipr[{a_, b_}]:=a(a+1)b(b+1); Take[Union[bipr/@Subsets[Range[0, 40], {2}]], 50] (* Harvey P. Dale, Jun 01 2012 *) CROSSREFS Cf. A054731, A054734, A072389. Sequence in context: A102749 A085231 A057715 * A026365 A051435 A187975 Adjacent sequences:  A053987 A053988 A053989 * A053991 A053992 A053993 KEYWORD nonn,easy AUTHOR Stuart M. Ellerstein (ellerstein(AT)aol.com), Apr 04 2000 EXTENSIONS More terms from James A. Sellers, Apr 22 2000 STATUS approved

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Last modified September 28 22:03 EDT 2020. Contains 337417 sequences. (Running on oeis4.)