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 A085242 #24 Feb 05 2025 10:12:23 %S A085242 0,1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,0,1,0,1,0, %T A085242 0,1,0,1,0,0,1,0,1,0,0,1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,0,1,0,1,0,0,1,0, %U A085242 1,0,0,1,0,1,0,0,1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,0,1,0,1,0,0,1,0,1,0,0 %N A085242 a(n) = A085239(n+1) - 2. %o A085242 (PARI) upto(L) = my(v2=2, v3=1, r=List()); while(v3<L, v3*=3; while(v2<v3 && v2<=L, listput(~r, 0); v2*=2); v3<=L && listput(~r, 1)); Vec(r); \\ _Ruud H.G. van Tol_, May 10 2024 %o A085242 (Python) %o A085242 from sympy import integer_log %o A085242 def A085242(n): return int(6**integer_log(m:=3**n,6)[0]<<1>=m) # _Chai Wah Wu_, Feb 05 2025 %Y A085242 Cf. A085239. %K A085242 nonn %O A085242 1,1 %A A085242 _Reinhard Zumkeller_, Jun 22 2003 %E A085242 Name corrected by _Ruud H.G. van Tol_, May 10 2024