OFFSET
1,2
COMMENTS
Numerators are the same as those from the expansion of tan(x).
Unlike the "sine integral" function Si(x), it seems that there does not exist a "tan integral" function.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..100
FORMULA
A036279(n)*(2n-1).
MATHEMATICA
a[n_] := Denominator[(-1)^(n-1)*4^n*(4^n-1)*BernoulliB[2*n]/(2*n)!]*(2*n-1); Table[a[n], {n, 1, 17}]
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Jean-François Alcover, May 30 2013
STATUS
approved