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 A088739 #14 Feb 16 2015 16:17:02
%S A088739 4,6,4,9,10,4,14,15,4,6,4,21,22,4,25,26,9,4,6,4,33,34,35,4,38,39,4,6,
%T A088739 4,9,46,4,49,10,51,4,6,55,4,57,58,4,62,9,4,65,6,4,69,10,4,74,15,4,77,
%U A088739 6,4,9,82,4,85,86,87,4,6,91,4,93,94,95,4,14,9,4,6,4,15,106,4,10,111,4
%N A088739 Smallest semiprime divisor of n-th composite number.
%C A088739 This is to semiprimes A001358 as A052369 is to primes A000040. - _Jonathan Vos Post_, Jan 11 2011
%H A088739 Zak Seidov, <a href="/A088739/b088739.txt">Table of n, a(n) for n = 1..1000</a>
%t A088739 semiPrimeQ[n_] := Plus @@ Last /@ FactorInteger@ n == 2; f[n_] := Min@ Select[ Divisors@ n, semiPrimeQ] /. {\[Infinity] -> 0}; f /@ Rest@ Select[ Range@ 112, !PrimeQ@ # &]
%t A088739 Reap[Do[If[! PrimeQ[n], Sow[Select[Divisors[n], PrimeOmega[#] == 2 &][[1]]]],{n, 4, 1200}]][[2, 1]] (* _Zak Seidov_, Mar 18 2013 *)
%Y A088739 Cf. A088740, A002808, A001358.
%K A088739 nonn
%O A088739 1,1
%A A088739 _Reinhard Zumkeller_, Oct 12 2003