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 A146327 #22 Jul 12 2021 03:36:43
%S A146327 2,3,10,11,12,15,21,26,27,30,35,45,50,51,56,63,77,82,83,84,87,90,93,
%T A146327 99,117,122,123,132,143,165,170,171,182,195,221,226,227,228,230,231,
%U A146327 235,237,240,245,255,285,290,291,306,323,357,362,363,380,399,437,442,443
%N A146327 Numbers k such that the continued fraction of (1 + sqrt(k))/2 has period 2.
%C A146327 For primes in this sequence see A056899, primes of the form k^2 + 2.
%H A146327 Amiram Eldar, <a href="/A146327/b146327.txt">Table of n, a(n) for n = 1..10000</a>
%e A146327 a(1) = 2 because continued fraction of (1 + sqrt(2))/2 = 1, 4, 1, 4, 1, 4, 1, ... has repeating part (1,4), period 2.
%p A146327 A146326 := proc(n) if not issqr(n) then numtheory[cfrac]( (1+sqrt(n))/2, 'periodic','quotients') ; nops(%[2]) ; else 0 ; fi; end: isA146327 := proc(n) RETURN(A146326(n) = 2) ; end: for n from 2 to 450 do if isA146327(n) then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Sep 06 2009
%t A146327 Select[Range[1000], 2 == Length[ContinuedFraction[(1 + Sqrt[#])/2][[2]]] &]
%Y A146327 Cf. A000290, A078370, A146326-A146345, A146348-A146360.
%K A146327 nonn
%O A146327 1,1
%A A146327 _Artur Jasinski_, Oct 30 2008
%E A146327 226, 227, 290, 291 added by _R. J. Mathar_, Sep 06 2009