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 A216295 #17 Jun 21 2022 04:24:01
%S A216295 18,21,24,42,63,66,69,81,102,105,117,120,138,147,151,153,180,181,183,
%T A216295 195,216,222,225,231,252,262,273,286,297,300,312,319,327,333,336,339,
%U A216295 357,393,411,420,423,426,462,469,480,483,486,501,526,528,535,553,558
%N A216295 Values of k such that 10k + 1 is the only prime between 10k and 10k + 9.
%H A216295 V. Raman, <a href="/A216295/b216295.txt">Table of n, a(n) for n = 1..10000</a>
%F A216295 a(n) ~ 0.4 n log n. - _Charles R Greathouse IV_, Sep 07 2012
%t A216295 t = {}; Do[ps = Select[Range[10*n, 10*n + 9], PrimeQ]; If[ps == {10*n + 1}, AppendTo[t, n]], {n, 0, 669}]; t (* _T. D. Noe_, Sep 03 2012 *)
%Y A216295 Cf. A032352, A007811, A078494.
%K A216295 nonn
%O A216295 1,1
%A A216295 _V. Raman_, Sep 03 2012