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 A376206 #5 Sep 15 2024 22:04:55 %S A376206 3,5,7,11,13,17,19,23,29,37,41,43,47,53,61,71,73,89,97,107,131,149, %T A376206 157,163,167,179,193,197,211,223,233,251,257,269,271,277,281,307,313, %U A376206 337,359,389,401,409,419,431,439,443,457,467,503,509,521,541,571,613,641,673,691 %N A376206 Prime indices of triangular numbers k such that either k + 1 or k - 2 is prime. %D A376206 David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See entry 496 at p. 155. %e A376206 29 is a term since it is prime and A000217(29) - 2 = 433 is prime. %t A376206 Select[Range[700], PrimeQ[#]&&(PrimeQ[t=#(#+1)/2+1]||PrimeQ[t-3]) &] %Y A376206 Cf. A000040 (supersequence), A000124, A000217, A034856. %Y A376206 Complement of A376205 in A000040. %K A376206 nonn,easy %O A376206 1,1 %A A376206 _Stefano Spezia_, Sep 15 2024