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 A272170 #31 Feb 07 2018 18:16:22 %S A272170 0,1,0,0,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0,0,1, %T A272170 0,0,1,1,0,1,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0, %U A272170 0,1,0,0,1,1,0,1,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0,0,1,0,0,1,0,0,1,1,0,0,1,0,0,1,0,0,1,1,0,1,1,0,0,1,0 %N A272170 Second most significant bit of Fibonacci numbers > 1 written in base 2. %C A272170 It is conjectured that there are no more than two consecutive "0's" or ā1āsā (tested up to n=10^5). The sequence looks quasiperiodic and its Fourier spectrum seems to have a fractal structure. %H A272170 Chai Wah Wu, <a href="/A272170/b272170.txt">Table of n, a(n) for n = 3..10000</a> %F A272170 a(n) = floor(A000045(n)/(2^(ceiling(log_2(A000045(n) + 1)) - 2))) - 2. %F A272170 a(n) = A079944(A000045(n)-2). - _Michel Marcus_, Apr 22 2016 %e A272170 (second MSB in parenthesis) %e A272170 n A000045(n) A004685(n) %e A272170 3 2 -> 1(0) %e A272170 4 3 -> 1(1) %e A272170 5 5 -> 1(0)1 %e A272170 6 8 -> 1(0)00 %e A272170 7 13 -> 1(1)01 %e A272170 8 21 -> 1(0)101 %e A272170 9 34 -> 1(0)0010 %e A272170 10 55 -> 1(1)0111 %e A272170 ... %t A272170 nmax = 120; Table[IntegerDigits[Fibonacci[j], 2][[2]], {j, 3, nmax}] %o A272170 (PARI) a(n) = binary(fibonacci(n))[2]; \\ _Michel Marcus_, Apr 25 2016 %o A272170 (Python) %o A272170 A272170_list, a, b = [], 1 ,1 %o A272170 for n in range(3,10001): %o A272170 a, b = b, a+b %o A272170 A272170_list.append(int(bin(b)[3])) # _Chai Wah Wu_, Feb 07 2018 %Y A272170 Cf. A000045, A004685, A079944, A271591. %K A272170 nonn,base %O A272170 3,1 %A A272170 _Andres Cicuttin_, Apr 21 2016