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 A259172 #27 Jul 17 2015 15:09:53 %S A259172 561,595,1105,1235,1245,1495,1547,1885,2405,2555,2717,2849,3115,3495, %T A259172 3655,3657,3689,3815,4521,4795,4945,5035,5385,5395,5453,5457,5709, %U A259172 5865,6083,6141,6251,6285,6365,6391,6501,6695,6755,6969,7021,7887,8113,8255,8355 %N A259172 Numbers in A259145 that are neither prime nor semiprime. %C A259172 Regarding the distribution: Let K be the union of primes and semiprimes in A259145. Let S be the set of other terms. The growth rate of the cardinality of S with respect to the cardinality of K is significantly slower. For instance, if we take the first 50000 terms of A259145, about 32.5 percent are contained in S. If we take the first 350000 terms, about 38.2 percent are contained in S. %C A259172 a(n) that are in A002997 (Carmichael numbers) for a(n) <= 10^6 are 561, 1105, 8911, 10585, 29341, 825265. %C A259172 a(n) that are in A051015 (Zeisel numbers) for a(n) <= 3*10^6 are 1885, 353977, 2953711. %H A259172 Carlos Eduardo Olivieri, <a href="/A259172/b259172.txt">Table of n, a(n) for n = 1..8906</a> %H A259172 Eric Naslund, <a href="http://arxiv.org/abs/1203.2363">Integers with a predetermined prime factorization</a>, arXiv:1203.2363 [math.NT], 2012. %F A259172 A001221(a(n)) > 2. %F A259172 A000005(a(n)) = 2^k, k >= 3. %t A259172 Select[Range[25000], PrimeQ[#^2 - EulerPhi[#]] && PrimeNu[#] > 2 &] %Y A259172 Cf. A001221, A001358, A002997, A007053, A051015, A125527, A259145. %Y A259172 Subsequence of A000469, A033942, A050384 (conjuctered). %K A259172 nonn,easy %O A259172 1,1 %A A259172 _Carlos Eduardo Olivieri_, Jun 19 2015