a(n) = (1/6)*n!*[x^n] (2 + sec(3*x) + tan(3*x) + 3*sec(x) + 3*tan(x)).

A320957

a(n) = (1/6)*n!*[x^n] (2 + sec(3*x) + tan(3*x) + 3*sec(x) + 3*tan(x)).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =10a(4) =70a(5) =656a(6) =7442a(7) =99280a(8) =1515190a(9) =26038016a(10) =497227682a(11) =10445708800a(12) =239394707110

External references