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A066396
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Reversion of j-function (see A000521).
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5
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1, -744, 910188, -1348239200, 2212373200878, -3870035739603792, 7072625493441991016, -13343943944697578921664, 25793763474486715046892405, -50818736423094538469855431992, 101675138631197524697523625818636, -206021386741542411973931322075432864
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OFFSET
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-1,2
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COMMENTS
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To get Maple to produce this, form t := series expansion of q^2 * j, and then do solve(t=y, y).
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LINKS
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FORMULA
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a(n) ~ c * (-1)^(n+1) * d^n / n^(3/2), where d = 2311.394562122568826864554431309352700589081544164805515755738565159053682... and c = 1943.54943209790549766737504313567156926515672546456731498696867555099... - Vaclav Kotesovec, Jun 28 2017, updated Mar 07 2018
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EXAMPLE
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If we write t = q^2*j = x + 744*x^2 + 196884*x^3 + ..., then x = t - 744*t^2 + 910188*t^3 - ...
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MATHEMATICA
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f[q_] = q^2*1728*KleinInvariantJ[ Log[q]/(2*Pi*I) ]; Rest[ CoefficientList[ InverseSeries[ Series[ f[q], {q, 0, 12}] ], q] ] (* Jean-François Alcover, Feb 17 2012 *)
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PROG
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(PARI) Vec(serreverse(q^2*ellj(q+O(q^15)))) \\ Joerg Arndt, Feb 25 2012
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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