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 A024236 Expansion of log(1+tan(x)*x)/2. 1
 0, 1, -2, 48, -1040, 62720, -4314624, 498003968, -70081316864, 13529482592256, -3175495421788160, 933402531586899968, -326784893253162369024, 136568449424117316190208, -66517446960602151366164480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA E.g.f. of aerated sequence: Sum(n>=0, a(n)*x^(2*n)/(2*n)!) = log(1+tan(x)*x)/2. - Robert Israel, Jun 29 2015 MAPLE S:= series(log(1+tan(x)*x)/2, x, 101): seq(coeff(S, x, 2*j)*(2*j)!, j=0..50); # Robert Israel, Jun 29 2015 MATHEMATICA With[{nn=30}, Take[CoefficientList[Series[Log[1+Tan[x]x]/2, {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jun 24 2018 *) CROSSREFS Cf. A009379. Cf. A101921. Sequence in context: A013523 A260846 A009670 * A119703 A012803 A135394 Adjacent sequences:  A024233 A024234 A024235 * A024237 A024238 A024239 KEYWORD sign AUTHOR EXTENSIONS Extended with signs, Mar 1997 Previous Mathematica program replaced by Harvey P. Dale, Jun 24 2018 STATUS approved

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Last modified January 17 10:30 EST 2019. Contains 319218 sequences. (Running on oeis4.)