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 A309697 #11 Aug 13 2019 05:34:35
%S A309697 0,0,2,5,2,5,4,1,8,0,1,5,5,1,7,1,7,2,7,7,2,8,6,7,2,7,0,3,6,4,3,7,1,3,
%T A309697 7,3,1,0,5,7,4,6,0,9,2,9,6,5,4,2,5,9,7,5,7,5,5,8,3,7,6,4,4,1,2,1,2,7,
%U A309697 2,4,7,1,3,7,7,7,9,6,1,7,8,2,8,3,2,3,8,9,0,0,9,3,9,9,7,9,3,4,9,0
%N A309697 a(n) is the digit that precedes the last nonzero digit of n^n.
%C A309697 Chu proves that the constant 0.00252541801... is transcendental.
%H A309697 Hung Viet Chu, <a href="https://arxiv.org/abs/1908.03855">New Transcendental Numbers from Certain Sequences</a>, arXiv:1908.03855 [math.NT], 2019.
%t A309697 a[n_] := Floor[PowerMod[n/10^IntegerExponent[n, 10], n, 100]/10]; Array[a, 100] (* _Giovanni Resta_, Aug 13 2019 *)
%o A309697 (PARI) a(n) = {my(d=digits(n^n)); forstep (k=#d, 1, -1, if (d[k], if (k==1, return (0)); return (d[k-1]));); return(0);}
%Y A309697 Cf. A056849.
%K A309697 nonn,base
%O A309697 1,3
%A A309697 _Michel Marcus_, Aug 13 2019