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 A065005 #3 Mar 30 2012 17:30:36
%S A065005 2,6,12,19,20,29,30,41,42,54,55,56,70,71,72,88,89,90,107,108,109,110,
%T A065005 129,130,131,132,153,154,155,156,178,179,180,181,182,206,207,208,209,
%U A065005 210,236,237,238,239,240,267,268,269,270,271,272,301,302,303,304,305
%N A065005 Integers for which the periodic part of the continued fraction for the square root of n begins with 2.
%e A065005 The continued fraction for the square root of 12 is 3, {2, 6}.
%t A065005 Select[ Range[500], First[ Last[ ContinuedFraction[ Sqrt[ # ]]]] == 2 & ]
%K A065005 easy,nonn
%O A065005 1,1
%A A065005 _Robert G. Wilson v_, Nov 01 2001