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 A291771 #8 Sep 11 2017 19:47:46 %S A291771 1,1,2,1,1,2,1,1,4,2,2,2,1,1,2,1,1,4,2,2,2,1,1,2,1,1,8,4,4,6,2,2,6,2, %T A291771 2,4,2,2,2,1,1,2,1,1,4,2,2,2,1,1,2,1,1,8,4,4,6,2,2,6,2,2,4,2,2,2,1,1, %U A291771 2,1,1,4,2,2,2,1,1,2,1,1,16,8,8,12,4,4,12,4,4,12,6,6,6,2,2,6,2,2,12,6,6,6,2,2,6 %N A291771 Filter based on runlengths of 0-digits in base-3 expansion of n: a(n) = A278222(A291770(n)). %H A291771 Antti Karttunen, <a href="/A291771/b291771.txt">Table of n, a(n) for n = 1..59049</a> %F A291771 a(n) = A278222(A291770(n)). %t A291771 f[n_, i_, x_] := Which[n == 0, x, EvenQ@ n, f[n/2, i + 1, x], True, f[(n - 1)/2, i, x Prime@ i]]; Array[If[# == 1, 1, Times @@ MapIndexed[Prime[First[#2]]^#1 &, Sort[FactorInteger[#][[All, -1]], Greater]]] &@ f[FromDigits[IntegerDigits[#, 3] /. k_ /; k < 3 :> If[k == 0, 1, 0], 2], 1, 1] &, 96] (* _Michael De Vlieger_, Sep 11 2017 *) %Y A291771 Cf. A007089, A077267, A278222, A291770, A290091, A290092, A290093, A290094. %K A291771 nonn,base %O A291771 1,3 %A A291771 _Antti Karttunen_, Sep 11 2017