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 A064748 #29 May 04 2025 04:45:10
%S A064748 1,11,201,3001,40001,500001,6000001,70000001,800000001,9000000001,
%T A064748 100000000001,1100000000001,12000000000001,130000000000001,
%U A064748 1400000000000001,15000000000000001,160000000000000001,1700000000000000001,18000000000000000001,190000000000000000001
%N A064748 a(n) = n*10^n + 1.
%C A064748 Number of digits in (10^n)^(10^n) in base 10. - _Altug Alkan_, Apr 25 2016
%H A064748 Vincenzo Librandi, <a href="/A064748/b064748.txt">Table of n, a(n) for n = 0..1000</a>
%H A064748 Paul Leyland, <a href="http://www.leyland.vispa.com/numth/factorization/main.htm">Cullen and Woodall numbers and their generalization to other bases</a>.
%H A064748 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (21,-120,100).
%F A064748 From _Ilya Gutkovskiy_, Apr 25 2016: (Start)
%F A064748 O.g.f.: (1 - 10*x + 90*x^2)/((1 - x)*(1 - 10*x)^2).
%F A064748 E.g.f.: (1 + 10*x*exp(9*x))*exp(x). (End)
%F A064748 From _Elmo R. Oliveira_, May 03 2025: (Start)
%F A064748 a(n) = 21*a(n-1) - 120*a(n-2) + 100*a(n-3).
%F A064748 a(n) = A126431(n) + 1. (End)
%t A064748 Table[n 10^n + 1, {n, 0, 18}] (* _Michael De Vlieger_, Apr 25 2016 *)
%o A064748 (Magma) [ n*10^n+1: n in [0..20]]; // _Vincenzo Librandi_, Sep 16 2011
%o A064748 (PARI) a(n) = n*10^n + 1; \\ _Altug Alkan_, Apr 25 2016
%Y A064748 Cf. A002064, A126431.
%K A064748 easy,nonn
%O A064748 0,2
%A A064748 _N. J. A. Sloane_, Oct 19 2001