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 A013607 #16 May 28 2023 16:26:55
%S A013607 1,5,5,5,17,7,17,7,7,7,59,19,17,13,7,19,49,13,19,7,23,35,19,89,17,119,
%T A013607 29,55,5,19,5,59,85,5,17,35,59,83,49,115,19,23,43,109,103,7,23,19,7,
%U A013607 245,43,13,5,55,89,83,143,53,53,383,7,55,113,37,5,23,143,115
%N A013607 a(n) = 6^n-prevprime(6^n).
%H A013607 Daniel Starodubtsev, <a href="/A013607/b013607.txt">Table of n, a(n) for n = 1..1000</a>
%F A013607 a(n) = A000400(n) - A104091(n). - _Michel Marcus_, Jan 13 2020
%p A013607 seq(6^i-prevprime(6^i),i=1..100);
%t A013607 pp[n_]:=Module[{n6=6^n},n6-NextPrime[n6,-1]]; Array[pp,70] (* _Harvey P. Dale_, May 04 2011 *)
%t A013607 #-NextPrime[#,-1]&/@(6^Range[70]) (* _Harvey P. Dale_, May 28 2023 *)
%Y A013607 Cf. A000400 (6^n), A104091 (largest prime <= 6^n).
%K A013607 nonn
%O A013607 1,2
%A A013607 James Kilfiger (mapdn(AT)csv.warwick.ac.uk)