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 A227432 #22 Feb 24 2018 12:58:54
%S A227432 3,3,9,99,189,33,453,123,93,597,69,189,279,1173,399,1719,2733,2493,87,
%T A227432 753,213,537,249,663,3309,123,279,597,2253,2853,3237,2403,6747,1257,
%U A227432 3069,159,3933,2277,6057,7557,1869,17043,2463,17013,4923,4767,15723,2607,2763
%N A227432 Difference between 10^n and the first prime of gap 4 > 10^n.
%C A227432 As N increases, the ratio sum(a(n)/n^2)/N for n = 1 to N tends to 4.
%H A227432 Pierre CAMI, <a href="/A227432/b227432.txt">Table of n, a(n) for n = 1..272</a>
%e A227432 10^1+3 = 13, 13 and 17 primes of gap 4, a(1)=3.
%e A227432 10^2+3 = 103, 103 and 107 primes of gap 4, a(2)=3.
%o A227432 (PARI) a(n) = {p = nextprime(10^n); q = nextprime(p+1); while (q-p != 4, r = nextprime(q+1); p = q; q = r); p - 10^n;} \\ _Michel Marcus_, Feb 24 2018
%Y A227432 Cf. A124001.
%K A227432 nonn
%O A227432 1,1
%A A227432 _Pierre CAMI_, Jul 11 2013
%E A227432 Missing a(246) inserted into b-file by _Andrew Howroyd_, Feb 24 2018