1,3

Series[Cosh[x]/(Sqrt[Cosh[x]^2 + Sinh[x]^2]), {x, 0, 20}]

cc=CoefficientList[Series[Sinh[x]/(Sqrt[Cosh[x]^2+Sinh[x]^2]), {x, -, 26}], x]; kk={}; Do[AppendTo[kk, Abs[Numerator[cc[[k]]]], {k, 2, Length[cc], 2]; kk

Cf. A012085, A012193.

Sequence in context: A012182 A012029 A012193 this_sequence A012085 A012221 A012144

Adjacent sequences: A128271 A128272 A128273 this_sequence A128275 A128276 A128277

nonn

Artur Jasinski (grafix(AT)csl.pl), Feb 22 2007