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 A242215 #17 Dec 08 2024 16:07:22
%S A242215 5,23,41,59,77,95,113,131,149,167,185,203,221,239,257,275,293,311,329,
%T A242215 347,365,383,401,419,437,455,473,491,509,527,545,563,581,599,617,635,
%U A242215 653,671,689,707,725,743,761,779,797,815,833,851,869,887,905,923,941,959
%N A242215 a(n) = 18*n + 5.
%C A242215 Conjecture: there are infinitely many composite Fermat numbers such that no one of them has a divisor that belongs to this sequence.
%H A242215 Wikipedia, <a href="http://en.wikipedia.org/wiki/Fermat_number">Fermat number</a>.
%H A242215 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A242215 G.f.: (5 + 13*x)/(1 - x)^2.
%F A242215 From _Elmo R. Oliveira_, Dec 08 2024: (Start)
%F A242215 E.g.f.: exp(x)*(5 + 18*x).
%F A242215 a(n) = 2*a(n-1) - a(n-2) for n > 1. (End)
%p A242215 seq(18*n+5, n=0..53);
%t A242215 Table[18*n + 5, {n, 0, 53}]
%t A242215 LinearRecurrence[{2,-1},{5,23},60] (* _Harvey P. Dale_, Aug 25 2017 *)
%o A242215 (Magma) [18*n+5: n in [0..53]];
%o A242215 (PARI) for(n=0, 53, print1(18*n+5, ", "));
%Y A242215 Supersequence of A061240.
%Y A242215 Cf. A229855.
%K A242215 nonn,easy
%O A242215 0,1
%A A242215 _Arkadiusz Wesolowski_, May 07 2014