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 A319042 #9 Sep 11 2018 11:03:40 %S A319042 35,169,385,899,961,1121,2001,3107,4879,4901,5719,6215,6265,6441,6479, %T A319042 6601,7055,7801,8119,8339,9799,10403,10763,10945,13079,13601,15841, %U A319042 18241,19097,20833,20951,22499,24727,27839,29183,29953,30731,31417,31535,34561,37345 %N A319042 Composite numbers k such that Pell(k) == 1 (mod k). %C A319042 It appears that most of the terms of A319040 (Numbers k such that Pell(k) == 1 (mod k)) are primes; this sequence lists the composites. %C A319042 For the composite numbers k such that Pell(k) == -1 (mod k), see A319043. %H A319042 Seiichi Manyama, <a href="/A319042/b319042.txt">Table of n, a(n) for n = 1..500</a> %e A319042 k=35 is in the sequence: Pell(35) = 8822750406821 = 35*252078583052 + 1 == 1 (mod 35). %e A319042 k=6 is not in the sequence: Pell(6) = 70 = 6*12 - 2 !== 1 (mod 6). %Y A319042 Cf. A000129 (Pell numbers), A094394, A319040, A319041, A319043. %K A319042 nonn %O A319042 1,1 %A A319042 _Jon E. Schoenfield_, Sep 08 2018