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 A101947 #10 Mar 02 2015 02:25:24
%S A101947 1,2,3,4,5,6,7,8,9,10,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,
%T A101947 28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,
%U A101947 51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73
%N A101947 A101909 sorted and duplicates removed.
%H A101947 Charles R Greathouse IV, <a href="/A101947/b101947.txt">Table of n, a(n) for n = 1..10000</a>
%o A101947 (PARI) bet2n4n(n) = { local(c,c1,x,y); a=vector(5001); for(x=1,n, c=0; forprime(y=2*x+1,4*x-1, c++; ); a[x] = c; ); b=vecsort(a); for(x=1,5000, if(b[x]>0, if(b[x]<>b[x+1],print1(b[x]",") ) ); ) }
%o A101947 (PARI) s=0;v=vectorsmall(10^6,n,s+=isprime(4*n-1)+isprime(4*n-3)-isprime(2*n-1));v=vecsort(v,,8);vecextract(v,Str("1..",#v\2)) \\ _Charles R Greathouse IV_, Mar 12 2012
%Y A101947 Cf. A101909, A101983-A101985.
%K A101947 easy,nonn
%O A101947 1,2
%A A101947 _Cino Hilliard_, Jan 28 2005