Period length of continued fraction for square root of n-th decimal repunit.

Terms

a(0) =2a(1) =6a(2) =2a(3) =24a(4) =2a(5) =622a(6) =2a(7) =2396a(8) =2a(9) =21912a(10) =2a(11) =527718a(12) =2a(13) =168484a(14) =2a(15) =13171730a(16) =2a(17) =359947864a(18) =2a(19) =52090778a(20) =2a(21) =16658818532a(22) =2a(23) =134257065348a(24) =2a(25) =61403998114a(26) =2