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 A089170 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]). 5
 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; text; internal format)
 OFFSET 0,12 COMMENTS Ratios of two similar sequences. This sequence is related to the sequences of the numerators and denominators of the Taylor series for tan(x), i.e., A002430 and A036279, and the similar sequences A160469 and A156769. - Johannes W. Meijer, May 24 2009 LINKS Michael De Vlieger, Table of n, a(n) for n = 0..5000 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 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 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}] CROSSREFS Cf. A002425. From Johannes W. Meijer, May 24 2009: (Start) Equals A160469(n+1)/A002430(n+1). Equals A156769(n+1)/A036279(n+1). (End) Sequence in context: A176728 A300909 A088469 * A040292 A040293 A040294 Adjacent sequences:  A089167 A089168 A089169 * A089171 A089172 A089173 KEYWORD nonn AUTHOR Wouter Meeussen, Dec 07 2003 STATUS approved

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Last modified June 17 22:14 EDT 2021. Contains 345086 sequences. (Running on oeis4.)