Triangle read by rows: T(n, k) = (-1)^(n-k) * (2*n + 1)! * [y^(2*k)] [x^(2*n+1)] arctan(sec(x*y)*tanh(x)).
A371687
Triangle read by rows: T(n, k) = (-1)^(n-k) * (2*n + 1)! * [y^(2*k)] [x^(2*n+1)] arctan(sec(x*y)*tanh(x)).
Terms
- a(0) =1a(1) =4a(2) =3a(3) =80a(4) =80a(5) =25a(6) =3904a(7) =5376a(8) =2660a(9) =427a(10) =354560a(11) =626688a(12) =433440a(13) =131712a(14) =12465a(15) =51733504a(16) =111738880a(17) =99242880a(18) =43804992a(19) =9021540a(20) =555731a(21) =11070525440a(22) =28258074624a(23) =30647302400a(24) =17666508288a(25) =5509286640a(26) =816337808a(27) =35135945
External references
- oeis: A371687