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 A076995 #6 Dec 05 2013 19:55:48 %S A076995 4,6,10,18,35,69,136,270,539,1077,2152,4303,8605,17208,34415,68829, %T A076995 137657,275313,550625,1101249,2202497,4404993,8809985,17619969, %U A076995 35239936,70479871,140959741,281919481,563838961,1127677921,2255355841 %N A076995 a(1) = 4, a(n+1) is the largest composite number < 2a(n). %p A076995 a[1] := 4:for n from 2 to 84 do q := 2*a[n-1]-1:while(isprime(q)) do q := q-1:od: a[n] := q:od:seq(a[l],l=1..84); %Y A076995 Cf. A006992, A076994. %K A076995 nonn %O A076995 1,1 %A A076995 _Amarnath Murthy_, Oct 26 2002 %E A076995 Corrected and extended by _Sascha Kurz_, Jan 26 2003