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 A377540 #29 Jul 23 2025 16:06:22 %S A377540 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,21,22,23,25,26,27,28, %T A377540 29,30,32,33,35,37,38,39,40,42,43,44,45,46,47,49,51,52,53,55,56,58,59, %U A377540 60,61,62,63,64,65,66,67,68,70,72,73,74,75,76,77,78,80,81,82,83,84,85,87 %N A377540 Numbers k such that at least one of the numbers 6k-1 or 6k+1 is prime. %t A377540 Select[Range[100], PrimeQ[6 # - 1] || PrimeQ[6 # + 1] &] %o A377540 (PARI) isok(k) = isprime(6*k-1) || isprime(6*k+1); \\ _Michel Marcus_, Oct 31 2024 %Y A377540 Union of A024898 and A024899. %Y A377540 Cf. A002476, A007528. %Y A377540 Complement of A060461 (with respect to the positive integers) or A171696 (with respect to the nonnegative integers). %K A377540 nonn,easy %O A377540 1,2 %A A377540 _Michel Eduardo Beleza Yamagishi_, Oct 31 2024