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 A335916 #13 Feb 25 2021 21:27:03 %S A335916 83,97,107,127,157,167,193,233,239,257,263,269,281,293,307,311,313, %T A335916 317,347,349,359,367,383,401,409,419,431,439,457,467,487,499,503,521, %U A335916 523,563,569,577,593,599,601,607,617,653,661,677,683,691,719,743,757,769,773,797,811,821,839,853 %N A335916 Isolated primes in the hexagonal spiral of the nonnegative integers. %C A335916 Plotting the integers on a hexagonal grid as in A001399 associates each n>=0 with six different neighbors to the E, NE, NW, W, SE and SW. If n is prime and all 6 neighbors are composite, n is in the sequence. %e A335916 The six neighbors of the prime 7 are 1, 6, 8, 18, 19, 20; 19 is also prime, so 7 is not in the sequence. %e A335916 The six neighbors of the prime 83 are 54, 55, 82, 84, 117 and 118 which are all composite, so 83 is in the sequence. %p A335916 # replace isA001358 by isprime in the coding for A113653, and isA113653 by isA335916. %Y A335916 Cf. A001399, A113653 (isolated semiprimes). %K A335916 nonn %O A335916 1,1 %A A335916 _R. J. Mathar_, Jun 29 2020