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 A068993 #22 May 07 2025 03:23:01
%S A068993 6,10,14,15,16,21,22,26,33,34,35,38,39,46,51,55,57,58,62,65,69,74,77,
%T A068993 81,82,85,86,87,91,93,94,95,106,111,115,118,119,122,123,129,133,134,
%U A068993 141,142,143,145,146,155,158,159,161,166,177,178,183,185,187,194,201
%N A068993 Numbers k such that A062799(k) = 4.
%C A068993 4*a(n)^2 are the solutions to A048272(x) = -Sum_{d|x} (-1)^d = -9. - _Benoit Cloitre_, Apr 14 2002
%H A068993 Amiram Eldar, <a href="/A068993/b068993.txt">Table of n, a(n) for n = 1..10000</a>
%F A068993 A113901(a(n)) = 4. - _Reinhard Zumkeller_, Mar 13 2011
%t A068993 f[n_] := DivisorSum[n, PrimeNu[#] &]; Select[Range[201], f[#] == 4 &] (* _Amiram Eldar_, Jul 25 2020 *)
%o A068993 (PARI) for(n=1,100,if(sumdiv(n,d,omega(d))==4,print1(n,",")))
%o A068993 (PARI) is(n)=my(f=factor(n)[,2]~); f==[1,1] || f==[4] \\ _Charles R Greathouse IV_, Oct 15 2015
%Y A068993 Union of A006881 and A030514.
%Y A068993 Cf. A048272, A062799, A113901.
%K A068993 easy,nonn
%O A068993 1,1
%A A068993 _Benoit Cloitre_, Apr 06 2002