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A114803
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Integers when g2^3-27*g3^2=0 in cubic polynomials of the form: w^2=4*x^3-g2*x-g3.
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0
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1, 3, 8, 12, 27, 27, 64, 48, 125, 75, 216, 108, 343, 147, 512, 192, 729, 243, 1000, 300, 1331, 363, 1728, 432, 2197, 507, 2744, 588, 3375, 675, 4096, 768, 4913, 867
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OFFSET
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0,2
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COMMENTS
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When the elliptic term: j=g2^3/(g2^3-27*g3^2) is singular and g2 and g3 are both integers.
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LINKS
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Table of n, a(n) for n=0..33.
Index entries for linear recurrences with constant coefficients, signature (0,4,0,-6,0,4,0,-1).
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FORMULA
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a(n) = If 3*n^(2/3) is an integer then {n,3*n^(2/3)}
a(n) = (n^3+6*n^2+12*n+8)/8 for n even. a(n) = (3*n^2+6*n+3)/4 for n odd. G.f.: -(3*x^5-x^4-4*x^2-3*x-1) / ((x-1)^4*(x+1)^4). - Colin Barker, Mar 15 2013
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MATHEMATICA
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a = Flatten[Table[If[IntegerQ[3*n^(2/3)] == True, {n, 3*n^(2/3)}, {}], {n, 1, 5000}]]
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CROSSREFS
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Sequence in context: A326890 A024463 A092954 * A083171 A058582 A178720
Adjacent sequences: A114800 A114801 A114802 * A114804 A114805 A114806
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KEYWORD
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nonn,uned,easy
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AUTHOR
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Roger L. Bagula, Feb 18 2006
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STATUS
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approved
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