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 A199768 #11 Feb 24 2020 08:12:08 %S A199768 4,6,8,12,16,18,20,24,27,30,32,36,40,42,45,48,50,54,56,60,64,70,72,75, %T A199768 80,81,84,90,96,100,105,108,112,120,126,128,132,135,140,144,150,160, %U A199768 162,168,180,189,192,196,198,200,210,216,220,224,225,240,243,250,252 %N A199768 Numbers whose greatest prime factor is less than their number of divisors. %C A199768 The greatest prime factor equals the number of divisors only for 1 (as defined in A006530) and numbers of the form p^(p-1) for p a prime. %H A199768 Amiram Eldar, <a href="/A199768/b199768.txt">Table of n, a(n) for n = 1..10000</a> %e A199768 4 has 2 as its greatest prime factor, and it has 3 factors (1, 2, 4), so it is in the sequence. %e A199768 10 has 5 as its greatest prime factor, but it has only 4 factors (1, 2, 5, 10), so it is not in the sequence. %t A199768 Select[Range[300],FactorInteger[#][[-1,1]]<DivisorSigma[0,#]&] (* _Harvey P. Dale_, Nov 19 2011 *) %Y A199768 Cf. A006530 (greatest prime factor), A000005 (number of divisors), A036878 (p^(p-1)). %K A199768 nonn,easy %O A199768 1,1 %A A199768 _Franklin T. Adams-Watters_, Nov 10 2011