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 A073432 #13 Oct 15 2013 22:31:27
%S A073432 1,4,8,12,15,17,21,23,26,30,33,35,38,40,44,46,49,53,55,58,61,63,66,68,
%T A073432 70,73,77,81,84,86,88,90,92,94,97,100,102,106,108,110,112,116,118,121,
%U A073432 123,126,129,131,134,136,140,142,144,146,150,154,156,158,160,162,165
%N A073432 Numbers n such that prime(n) + composite(n) is even.
%C A073432 For n > 1, numbers n such that the n-th composite number is odd. - _Charles R Greathouse IV_, Apr 03 2012
%H A073432 Charles R Greathouse IV, <a href="/A073432/b073432.txt">Table of n, a(n) for n = 1..10000</a>
%F A073432 Numbers n such that (A000040(n)+A002808(n))/2 is an integer.
%F A073432 a(n) ~ 2n since the primes have density 0. _Charles R Greathouse IV_, Apr 03 2012
%e A073432 8 is in the sequence since prime(8)=19, composite(8)=15, and their average 17 is an integer.
%t A073432 c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Do[s=(Prime[n]+c[n])/2; If[IntegerQ[s], Print[s]], {n, 1, 256}]
%o A073432 (PARI) print1(n=1);for(c=6,1e3,if(isprime(c),next);n++;if(c%2,print1(", "n))) \\ _Charles R Greathouse IV_, Apr 03 2012
%Y A073432 Cf. A000040, A002808.
%K A073432 nonn,easy
%O A073432 1,2
%A A073432 _Labos Elemer_, Jul 31 2002