(n-1)-st elementary symmetric function of the first n terms of (1,2,3,1,2,3,1,2,3,...).

Terms

a(0) =1a(1) =3a(2) =11a(3) =17a(4) =40a(5) =132a(6) =168a(7) =372a(8) =1188a(9) =1404a(10) =3024a(11) =9504a(12) =10800a(13) =22896a(14) =71280a(15) =79056a(16) =165888a(17) =513216a(18) =559872a(19) =1166400a(20) =3592512a(21) =3872448a(22) =8024832a(23) =24634368a(24) =26313984a(25) =54307584a(26) =166281984a(27) =176359680a(28) =362797056a(29) =1108546560