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 A012016 arctanh(sin(tan(x)))=x+3/3!*x^3+41/5!*x^5+1299/7!*x^7+74609/9!*x^9... 1
 1, 3, 41, 1299, 74609, 6787811, 898506649, 163241051315, 39007280136801, 11866656488375747, 4479287777805494665, 2054673461380880189779, 1125793481954983195433681, 726247496033154181534638755 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..13. FORMULA a(n) ~ 2 * (2*n)! / (arctan(Pi/2))^(2*n+1). - Vaclav Kotesovec, Oct 24 2013 MATHEMATICA Table[n!*SeriesCoefficient[ArcTanh[Sin[Tan[x]]], {x, 0, n}] , {n, 1, 40, 2}] (* Vaclav Kotesovec, Oct 24 2013 *) With[{nn=30}, Take[CoefficientList[Series[ArcTanh[Sin[Tan[x]]], {x, 0, nn}], x] Range[0, nn-1]!, {2, -1, 2}]] (* Harvey P. Dale, Oct 09 2018 *) CROSSREFS Bisection of A009329. Sequence in context: A012225 A012129 A012035 * A207993 A187540 A012104 Adjacent sequences: A012013 A012014 A012015 * A012017 A012018 A012019 KEYWORD nonn AUTHOR Patrick Demichel (patrick.demichel(AT)hp.com) STATUS approved

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Last modified June 3 23:57 EDT 2023. Contains 363118 sequences. (Running on oeis4.)