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 A181678 #23 Sep 06 2015 07:40:59
%S A181678 0,0,10,73,508,3468,25629,194614,1537504,12447679,102834428
%N A181678 Number of twin Ramanujan prime pairs less than 10^n.
%H A181678 J. Sondow, <a href="http://arxiv.org/abs/0907.5232"> Ramanujan primes and Bertrand's postulate</a>, Amer. Math. Monthly 116 (2009) 630-635.
%H A181678 J. Sondow, J. W. Nicholson, and T. D. Noe, <a href="http://arxiv.org/abs/1105.2249"> Ramanujan Primes: Bounds, Runs, Twins, and Gaps</a>, J. Integer Seq. 14 (2011) Article 11.6.2
%t A181678 nn=50000; t=Table[0,{nn}]; s=0; Do[If[PrimeQ[k], s++]; If[PrimeQ[k/2], s--]; If[s<nn, t[[s+1]]=k], {k, Prime[3*nn]}]; t=t+1; cnt=0; i=1; Table[While[t[[i]]<10^n, If[t[[i]]+2 == t[[i+1]], cnt++]; i++]; cnt, {n,Floor[Log[10,t[[-1]]]]}]
%o A181678 (Perl) use ntheory ":all"; for my $n (0..9) { my $r = ramanujan_primes(10**$n); my $t=0; for (0..$#$r-1) { $t++ if $r->[$_+1] - $r->[$_] == 2; } say "$n $t"; } # _Dana Jacobsen_, Sep 06 2015
%Y A181678 Cf. A178127 (lesser of twin Ramanujan primes), A007508 (number of twin primes pairs < 10^n), A190654 (twin Ramanujan primes).
%K A181678 nonn,more
%O A181678 1,3
%A A181678 _T. D. Noe_, Nov 18 2010
%E A181678 a(10)-a(11) from _Dana Jacobsen_, Apr 29 2015