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 A188136 #15 Apr 02 2020 03:03:14 %S A188136 61,317,461,557,773,1129,1429,1877,1901,4597,5417,6053,8761,10733, %T A188136 11621,13877,15277,16333,17737,18329,23593,30137,41453,45533,51893, %U A188136 59341,70429,74597,74857,80429,86201,92173,94321,94421,100733,104717 %N A188136 Primes p such that the period of the continued fraction of (1-sqrt(p))/2 has length 3 and p is not of the form k^2+1. %H A188136 Amiram Eldar, <a href="/A188136/b188136.txt">Table of n, a(n) for n = 1..500</a> (terms 1..75 from Vincenzo Librandi) %t A188136 Select[Prime[Range[100]], ! IntegerQ[Sqrt[# - 1]] && 3 == Length[ContinuedFraction[(1 + Sqrt[#])/2][[2]]] &] %Y A188136 Cf. A002496, A146348. %K A188136 nonn %O A188136 1,1 %A A188136 _Artur Jasinski_, Mar 21 2011