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A101922
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Numerators of expansion of 2^(-1/2) * arcsinh(cos(x)).
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2
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-1, -1, 11, 491, 11159, -460681, -103577629, -8160790429, 624333860399, 386787409545839, 68810049201689531, -6999828208693648549, -9872674440874152431161, -3255253386897615662908441
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| With sign pattern +--+--: numerators of expansion of 2^(-1/2) * asinh(cosh(x)).
Odd coefficients are zero, denominators are 2^n.
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FORMULA
| asinh(cos(x)) = log(sqrt(2)+1) + 1/sqrt(2) * [ -1/2*x^2/2! - 1/4*x^4/4! + 11/8*x^6/6! + 491/16*x^8/8! +...].
acosh(cos(x)) = Pi/2 - log(sqrt(2)+1) + 1/sqrt(2) * [1/2*x^2/2! + 1/4*x^4/4! - 11/8*x^6/6! - 491/16*x^8/8! -...].
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CROSSREFS
| Cf. A101924, A012495.
Sequence in context: A156863 A145516 A041931 * A142809 A139198 A004800
Adjacent sequences: A101919 A101920 A101921 * A101923 A101924 A101925
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KEYWORD
| sign
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AUTHOR
| Ralf Stephan, Dec 27 2004
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