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 A172487 #10 Mar 30 2012 18:40:08
%S A172487 3,17,29,41,71,101,137,149,191,197,239,269,281,311,419,431,461,521,
%T A172487 569,599,617,641,659,809,821,827,857,881,1031,1049,1061,1091,1151,
%U A172487 1229,1277,1289,1301,1427,1451,1481,1607,1667,1697,1721,1787,1871,1877,1931,1949,1997
%N A172487 Lesser of twin primes in A172240.
%C A172487 For a(n) > 3, the first differences of the sequence are divisible by 6. (Is this a conjecture or a theorem?)
%F A172487 A001359 INTERSECT A172240.
%p A172487 isA001359 := proc(p) isprime(p) and isprime(p+2) ; end proc:
%p A172487 isA000430 := proc(p) if isprime(p) then true; else if issqr(p) then isprime(sqrt(p)) ; else false; end if; end if; end proc:
%p A172487 isA181669 := proc(p) if isprime(p) and (p mod 6)= 5 then if numtheory[bigomega](p-1) =2 and isA000430(p+2) then true; else false; end if;else false; end if ; end proc:
%p A172487 isA172240 := proc(n) isprime(n) and not isA181669(n) ; end proc:
%p A172487 isA172487 := proc(n) isA172240(n) and isA001359(n) ; end proc:
%p A172487 for n from 2 to 2000 do if isA172487(n) then printf("%d,",n) ; end if;end do:
%Y A172487 Cf. A173176, A172240, A181669, A181602.
%K A172487 nonn,easy
%O A172487 1,1
%A A172487 _Giovanni Teofilatto_, Nov 21 2010