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 A067556 #10 Jun 16 2013 04:25:15 %S A067556 7,357,17857,892857,44642857,2232,111607,5580357,279017857, %T A067556 13950892857,697544642857,34877232,1743861607,87193080357, %U A067556 4359654017857,217982700892857,10899135044642857,544956752232,27247837611607 %N A067556 Terms in the decimal expansion of 1/(7*2^n) before the block of decimals 142857 (the period of 1/7) appears. %C A067556 Example : 1/(7*2^5) = 0.0044642857(142857...) where 142857 is the period of 1/7, hence a(5)=44642857. %F A067556 a(n)=(1/7)*(5^n*10^(n mod 6)-1). %F A067556 Empirical g.f.: x*(-44640625*x^5+43750000*x^4+875000*x^3+17500*x^2+350*x+7) / (15625*x^7-15625*x^6-x+1). - _Colin Barker_, Jun 16 2013 %o A067556 (PARI) a(n)=(1/7)*(5^n*10^(n%6)-1) %o A067556 (PARI) a(n)=if(n<0,0,s=1;while(frac(10^s/7/2^n-1/7)>0,s++);floor(10^s/7/2^n)) %K A067556 nonn,base %O A067556 1,1 %A A067556 _Benoit Cloitre_, Jan 29 2002; revised Dec 11, 2004