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 A086288 #16 Jan 06 2020 08:36:04 %S A086288 0,1,1,1,1,2,1,1,1,2,2,2,2,1,2,2,2,2,1,1,2,3,1,2,2,2,3,2,2,1,2,2,2,3, %T A086288 2,1,3,2,2,2,1,3,3,2,2,2,3,2,2,3,1,3,1,2,3,2,2,3,2,2,3,2,3,2,2,2,2,4, %U A086288 2,2,2,3,1,2,2,3,1,3,3,2,3,3,3,2,2,3,1,3,3,2,3,2,2,2,2,4,2,2,2,3 %N A086288 Number of distinct prime factors of 7-smooth numbers. %H A086288 Amiram Eldar, <a href="/A086288/b086288.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from G. C. Greubel) %F A086288 a(n) = A001221(A002473(n)). %F A086288 a(n) <= 4. %t A086288 PrimeNu[Select[Range[500], Max[Transpose[FactorInteger[#]][[1]]] <= 7 &]] (* _G. C. Greubel_, May 09 2017 *) %Y A086288 Cf. A001221, A002473, A086289, A086290. %K A086288 nonn %O A086288 1,6 %A A086288 _Reinhard Zumkeller_, Jul 15 2003