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 A086299 #24 Feb 16 2025 08:32:50
%S A086299 1,1,1,1,1,1,1,1,1,1,0,1,0,1,1,1,0,1,0,1,1,0,0,1,1,0,1,1,0,1,0,1,0,0,
%T A086299 1,1,0,0,0,1,0,1,0,0,1,0,0,1,1,1,0,0,0,1,0,1,0,0,0,1,0,0,1,1,0,0,0,0,
%U A086299 0,1,0,1,0,0,1,0,0,0,0,1,1,0,0,1,0,0,0,0,0,1,0,0,0,0,0,1,0,1,0,1,0,0
%N A086299 a(n) = if n is 7-smooth then 1 else 0: characteristic function of 7-smooth numbers.
%H A086299 Reinhard Zumkeller, <a href="/A086299/b086299.txt">Table of n, a(n) for n = 1..10000</a>
%H A086299 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/SmoothNumber.html">Smooth Number</a>.
%H A086299 <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>.
%F A086299 Multiplicative with: a(p) = if p<=7 then 1 else 0, p prime.
%F A086299 a(A002473(n)) = 1; a(A068191(n)) = 0. - _Reinhard Zumkeller_, Apr 01 2012
%F A086299 Dirichlet g.f.: 1/((1-2^(-s))*(1-3^(-s))*(1-5^(-s))*(1-7^(-s))). - _Amiram Eldar_, Dec 27 2022
%t A086299 Table[If[Max[Transpose[FactorInteger[n]][[1]]]<11,1,0],{n,110}] (* _Harvey P. Dale_, Oct 08 2013 *)
%t A086299 smooth7Q[n_] := n == Times@@({2, 3, 5, 7}^IntegerExponent[n, {2, 3, 5, 7}]);
%t A086299 a[n_] := Boole[smooth7Q[n]];
%t A086299 Table[a[n], {n, 1, 100}] (* _Jean-François Alcover_, Oct 17 2021 *)
%o A086299 (Haskell)
%o A086299 a086299 = fromEnum . (<= 7) . a006530 -- _Reinhard Zumkeller_, Apr 01 2012
%Y A086299 Cf. A002473, A006530, A068191.
%K A086299 nonn,mult
%O A086299 1,1
%A A086299 _Reinhard Zumkeller_, Jul 15 2003