Largest term in periodic part of continued fraction expansion of square root of -1+3^n.

Terms

a(0) =2a(1) =4a(2) =10a(3) =16a(4) =30a(5) =52a(6) =92a(7) =160a(8) =280a(9) =484a(10) =840a(11) =1456a(12) =2524a(13) =4372a(14) =7574a(15) =13120a(16) =22726a(17) =39364a(18) =68182a(19) =118096a(20) =204550a(21) =354292a(22) =613654a(23) =1062880a(24) =1840964a(25) =3188644a(26) =5522896a(27) =9565936a(28) =16568690a(29) =28697812