This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A061682 #31 Sep 29 2019 19:02:45
%S A061682 4,10,16,44,74,46,204,714,702,908,404,7754,1136,9886,8154,23578,65096,
%T A061682 404762,23992,3514774,110124,4802160,6490450,180832,115972,770304,
%U A061682 62665998,133093360,1019300318,60079334,113987888,5702124038,4463754028,713372392,38574516706,9096543466,7030527700,582442851838,16708770664,32628786870
%N A061682 Length of period of continued fraction expansion of square root of (2^(2n+1)+1).
%C A061682 Old definition was: "Quotient cycle length in continued fraction expansion of sqrt(2^(2n+1)+1)."
%F A061682 a(n) = A003285(A087289(n)). - _Michel Marcus_, Sep 26 2019
%t A061682 a[n_] := ContinuedFraction[Sqrt[2^(2n+1)+1]] // Last // Length; Table[a[n], {n, 2, 28}] (* _Jean-François Alcover_, Dec 11 2016 *)
%Y A061682 Cf. A003285, A059866, A059926, A087289.
%K A061682 nonn,nice,more
%O A061682 2,1
%A A061682 _Labos Elemer_, Mar 01 2001
%E A061682 One more term from _David W. Wilson_, Jun 18 2001
%E A061682 Corrected and extended by _Naohiro Nomoto_, Nov 09 2001
%E A061682 a(29)-a(31) from _Daniel Suteu_, Jan 25 2019
%E A061682 a(32) from _Chai Wah Wu_, Sep 23 2019
%E A061682 a(33)-a(38) from _Chai Wah Wu_, Sep 25 2019
%E A061682 Simpler definition from _Bernard Schott_, Sep 26 2019
%E A061682 a(39)-a(41) from _Chai Wah Wu_, Sep 29 2019