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 A109946 #10 Apr 03 2023 10:36:10 %S A109946 2,19,41,79,331,439,499,619,829,1031,1069,1279,1451,1481,1511,1811, %T A109946 1889,1901,1931,2089,2179,2791,3019,3109,3181,3449,3491,3769,3821, %U A109946 3911,4159,4231,4639,4861,4951,5081,5419,5441,5749,5849,6101,6131,6709,7151,7349 %N A109946 Smallest prime starting a complete two iterations Cunningham chain of the first and second kind. %C A109946 Intersection of A057326 and A059762. The terms have to start a chain through iteration by either <2p+1> or <2p-1> operator (not mixed in the same chain); and the chains has to be three primes long. %H A109946 Chris Caldwell, The Prime Glossary, <a href="https://t5k.org/glossary/page.php?sort=CunninghamChain">Cunningham chains</a>. %e A109946 a(1)=2 is here because 2 -> 3 -> 5 through <2p-1> and the chain ends here (with this operator). %e A109946 a(2)=19 is here because 19 -> 37 -> 73 through <2p-1>. %e A109946 a(3)=41 is here because 41 -> 83 -> 167 through <2p+1>. %e A109946 - 11 is not here because it is well followed by two terms, but doesn't start this sequence (2->5->11->23->47). %e A109946 - 89 is not here because it starts a 6 terms chain. %Y A109946 Cf. A057326, A059762. %K A109946 nonn %O A109946 1,1 %A A109946 _Alexandre Wajnberg_, Aug 31 2005 %E A109946 Terms computed by Gilles Sadowski.