a(n) = sinh(2*arccosh(n))^2 = 4*n^2*(n^2 - 1).

Terms

a(0) =0a(1) =0a(2) =48a(3) =288a(4) =960a(5) =2400a(6) =5040a(7) =9408a(8) =16128a(9) =25920a(10) =39600a(11) =58080a(12) =82368a(13) =113568a(14) =152880a(15) =201600a(16) =261120a(17) =332928a(18) =418608a(19) =519840a(20) =638400a(21) =776160a(22) =935088a(23) =1117248a(24) =1324800a(25) =1560000a(26) =1825200a(27) =2122848a(28) =2455488a(29) =2825760