O.g.f.: Sum_{n>=0} Product_{k=1..n} tan( (2*k-1)*arctan(x) ).

A295758

O.g.f.: Sum_{n>=0} Product_{k=1..n} tan( (2*k-1)*arctan(x) ).

Terms

    a(0) =1a(1) =1a(2) =3a(3) =15a(4) =113a(5) =1105a(6) =13219a(7) =187103a(8) =3058113a(9) =56675297a(10) =1174295267a(11) =26898243439a(12) =674916701169

External references