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A147530
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Numbers x such that there exists n in N : (x+1)^3 - x^3 = 103*n^2.
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5
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51721, 6641322533431006, 852782015075257741682069713, 109501859241899449111168441436054160358, 14060635620199598267351285586436862449157290510201, 1805462258017787769335954916623470050495526664967434749114126
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n+2) = 128405450990*a(n+1) - a(n) + 62402725494.
G.f.: x*(51721 + 64202725495*x - 51722*x^2)/((1-x)*(1 - 128405450990*x + x^2)). - Colin Barker, Oct 21 2014, corrected Jul 13 2016
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EXAMPLE
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a(1)=51721 because the first relation is : 51722^3 - 51721^3 = 103*8827^2.
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MAPLE
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seq(coeff(series(x*(51721+64202725495*x-51722*x^2)/((1-x)*(1-128405450990*x + x^2)), x, n+1), x, n), n = 1..20); # G. C. Greubel, Jan 12 2020
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MATHEMATICA
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LinearRecurrence[{128405450991, -128405450991, 1}, {51721, 6641322533431006, 852782015075257741682069713}, 20] (* G. C. Greubel, Jan 12 2020 *)
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PROG
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(PARI) Vec(x*(51721+64202725495*x-51722*x^2)/((1-x)*(1-128405450990*x+x^2)) + O(x^10)) \\ Colin Barker, Oct 21 2014, corrected Jul 13 2016
(PARI) isok(x) = issquare(((x+1)^3-x^3)/103) \\ Colin Barker, Jul 13 2016
(Magma) I:=[51721, 6641322533431006]; [n le 2 select I[n] else 128405450990*Self(n-1) - Self(n-2) + 62402725494: n in [1..20]]; // G. C. Greubel, Jan 12 2020
(Sage)
P.<x> = PowerSeriesRing(ZZ, prec)
return P( x*(51721+64202725495*x-51722*x^2)/((1-x)*(1-128405450990*x + x^2)) ).list()
(GAP) a:=[51721, 6641322533431006];; for n in [3..20] do a[n]:=128405450990*a[n-1] -a[n-2] +62402725494; od; a; # G. C. Greubel, Jan 12 2020
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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