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 A368619 #27 Jan 12 2024 22:21:47
%S A368619 1,4,323,939,14341,61716,1621261,9192919,324707423,509838905,
%T A368619 30546664503,59359795395,3329737379233,9164547454619
%N A368619 a(n) is the n-digit denominator of the fraction h/k with h and k coprime palindrome positive integers at which abs(h/k-e) is minimal.
%C A368619 a(3) = 323 corresponds to the denominator of A368617.
%H A368619 David A. Corneth, <a href="/A368618/a368618.gp.txt">PARI program</a>
%H A368619 <a href="/index/Ea">Index entries for sequences related to the number e</a>
%e A368619 n fraction approximated value
%e A368619 - ------------------- ------------------
%e A368619 1 3/1 3
%e A368619 2 11/4 2.75
%e A368619 3 878/323 2.7182662538699...
%e A368619 4 2552/939 2.7177848775292...
%e A368619 5 38983/14341 2.7182902168607...
%e A368619 6 167761/61716 2.7182740294251...
%e A368619 7 4407044/1621261 2.7182816338640...
%e A368619 8 24988942/9192919 2.7182815382143...
%e A368619 9 882646288/324707423 2.7182818299783...
%e A368619 ...
%t A368619 a[1]=1; a[n_]:=Module[{minim = Infinity}, h = Select[Range[10^(n - 1), 10^n - 1], PalindromeQ]; lh = Length[h]; For[i = 1, i <= lh, i++, k = Select[Range[Floor[Part[h, i]/E], Ceiling[Part[h, i]/E]], PalindromeQ]; lk = Length[k]; For[j = 1, j <= lk, j++, If[(dist = Abs[Part[h, i]/Part[k, j] - E]) < minim && GCD[Part[h, i], Part[k, j]] == 1, minim = dist; kmin = Part[k, j]]]]; kmin]; Array[a,9]
%o A368619 (PARI) \\ See PARI program in Links
%Y A368619 Cf. A001113, A002113, A070252, A368617, A368618 (numerator), A368658.
%Y A368619 Cf. A007676, A007677.
%Y A368619 Cf. A364845 (similar for Pi), A368620, A368621.
%K A368619 nonn,base,frac,more
%O A368619 1,2
%A A368619 _Stefano Spezia_, Jan 01 2024
%E A368619 a(10)-a(14) from _David A. Corneth_, Jan 03 2024