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 A126641 #10 Jun 13 2015 00:52:18 %S A126641 9,73,537,3625,22809,135913,777177,4308265,23329689,124104553, %T A126641 651267417,3382100905,17421964569,89180975593,454265623257, %U A126641 2304999893545,11660373751449,58845428989033,296407578308697,1490778208598185,7488908074594329,37584775814704873 %N A126641 a(n) is the number of integers k less than 10^n such that the decimal representation of k lacks the digit 1, at least one of digits 2,3, at least one of digits 4,5, at least one of digits 6,7 and at least one of digits 8,9. %H A126641 Colin Barker, <a href="/A126641/b126641.txt">Table of n, a(n) for n = 1..1000</a> %H A126641 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas for Some Functions on Finite Sets</a> %H A126641 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (15,-85,225,-274,120). %F A126641 a(n) = 16*5^n-32*4^n+24*3^n-8*2^n+1. %F A126641 G.f.: -x*(120*x^4-250*x^3+207*x^2-62*x+9) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)). - _Colin Barker_, Feb 22 2015 %p A126641 f:=n->16*5^n-32*4^n+24*3^n-8*2^n+1; %o A126641 (PARI) Vec(-x*(120*x^4-250*x^3+207*x^2-62*x+9) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)) + O(x^100)) \\ _Colin Barker_, Feb 22 2015 %Y A126641 Cf. A125630, A125948, A125947, A125946, A125945, A125940, A125909, A125908, A125880, A125897, A125904, A125858. %K A126641 nonn,base,easy %O A126641 1,1 %A A126641 Aleksandar M. Janjic and _Milan Janjic_, Feb 08 2007