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A089170
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Numerator of 2*BernoulliB[2*(n+1)]*(4^(n+1)-1)/(2*(n+1))] divided by numerator of the series coefficients of 1/(1 + Cosh[x]).
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4
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 17, 1, 1, 1, 1, 1, 1, 1, 527, 1, 1, 1, 1, 31, 1, 1, 731, 1, 41, 1, 1, 1, 37, 1333, 17, 1, 1, 1, 31, 1, 1, 1, 17, 73, 1, 1, 1, 43, 1271, 59, 629, 1, 73, 2759, 43, 1, 1, 1, 17, 1, 67, 7519, 1, 31, 89, 1, 289, 1, 29020032511, 1, 10573, 1, 1, 1, 2227, 486029
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,12
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COMMENTS
| Ratios of two similar sequences.
Contribution from Johannes W. Meijer (meijgia(AT)hotmail.com), May 24 2009: (Start)
This sequence is related to the sequences of the numerators and denominators in Taylor series for tan(x) , i.e. A002430 and A036279, and their 'look-a-likes', i.e. A160469 and A156769.
(End)
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FORMULA
| For n>=0, a(n)=c(n+1) where c(n)=numerator((4^n-1)*B(2*n)/n)/numerator((4^n-1)*B(2*n)/(2*n)!), B(k) denotes the k-th Bernoulli number. - C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 19 2004
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MAPLE
| seq(numer(2*bernoulli(2*n)*(4^n-1)/(2*n))/numer((4^n-1)*bernoulli(2*n)/(2*n)!), n=1..100); (C. Ronaldo)
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MATHEMATICA
| Table[Numerator[2*BernoulliB[2*n]*(4^n -1)/(2*n)]/Numerator[SeriesCoefficient[Series[1/(1+Cosh[x]), {x, 0, 2n}], 2n-2]], {n, 1, 128}]
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CROSSREFS
| Cf. A002425.
Contribution from Johannes W. Meijer (meijgia(AT)hotmail.com), May 24 2009: (Start)
Equals A160469(n+1)/A002430(n+1)
Equals A156769(n+1)/A036279(n+1)
(End)
Sequence in context: A144692 A176728 A088469 * A040292 A040293 A040294
Adjacent sequences: A089167 A089168 A089169 * A089171 A089172 A089173
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KEYWORD
| nonn
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AUTHOR
| Wouter Meeussen (wouter.meeussen(AT)pandora.be), Dec 07 2003
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