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 A235495 #18 Jan 12 2014 00:30:57 %S A235495 1,2,3,4,48,50,60,504,540,546,558,561,564,567,4204,4212,4220,4228, %T A235495 4232,4236,32270,32290,32305,32310,32325,32345,32350,32355,32360, %U A235495 240426,240432,240504,240510,240516,240522,240528,240534,240540,240546,240648,240678,240684 %N A235495 Numbers n such that pi(2n) divides n. %H A235495 Vincenzo Librandi, <a href="/A235495/b235495.txt">Table of n, a(n) for n = 1..59</a> %e A235495 48 is in the sequence because pi(2*48) = 24 and 24 divides 48. %t A235495 Select[Range[10^6],IntegerQ[#/PrimePi[2#]]&] %o A235495 (PARI) is(n)=n%primepi(2*n)==0 \\ _Charles R Greathouse IV_, Jan 12 2014 %Y A235495 Cf. A057809. %K A235495 nonn %O A235495 1,2 %A A235495 _Vincenzo Librandi_, Jan 11 2014