sech(arctanh(x)*cos(x))=1-1/2!*x^2+9/4!*x^4-225/6!*x^6+6993/8!*x^8...
A012749
sech(arctanh(x)*cos(x))=1-1/2!*x^2+9/4!*x^4-225/6!*x^6+6993/8!*x^8...
Terms
- a(0) =1a(1) =-1a(2) =9a(3) =-225a(4) =6993a(5) =-592545a(6) =38019993a(7) =-7568120833a(8) =704958936737
External references
- oeis: A012749