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 A280700 #20 Mar 08 2025 04:03:54
%S A280700 0,1,2,1,3,1,2,3,4,1,2,3,3,4,3,3,5,1,2,3,3,4,3,3,4,5,3,3,4,4,3,4,6,1,
%T A280700 2,3,3,4,3,3,4,5,3,3,4,4,3,4,5,6,3,3,4,4,3,4,5,5,3,4,4,5,6,4,7,1,2,3,
%U A280700 3,4,3,3,4,5,3,3,4,4,3,4,5,6,3,3,4,4,3,4,5,5,3,4,4,5,6,4,6,7,3,3,4,4,3,4,5,5,3,4,4,5,6,4,6,6,3,4,4,5,6,4,5
%N A280700 Binary weight of terms of A005187: a(n) = A000120(A005187(n)).
%H A280700 Antti Karttunen, <a href="/A280700/b280700.txt">Table of n, a(n) for n = 0..8191</a>
%F A280700 a(n) = A000120(A005187(n)).
%F A280700 a(n) = A001221(A283475(n)) = A001222(A283475(n)) = A001222(A280705(n)).
%t A280700 Table[DigitCount[2 n - DigitCount[2 n, 2, 1], 2, 1], {n, 0, 120}] (* _Michael De Vlieger_, Mar 18 2017 *)
%o A280700 (Scheme) (define (A280700 n) (A000120 (A005187 n)))
%o A280700 (PARI)
%o A280700 b(n) = if(n<1, 0, b(n\2) + n%2);
%o A280700 for(n=0, 150, print1(b(2*n - b(2*n)), ", ")) \\ _Indranil Ghosh_, Mar 21 2017
%o A280700 (Python)
%o A280700 def A(n): return bin(2*n - bin(2*n)[2:].count("1"))[2:].count("1")
%o A280700 print([A(n) for n in range(151)]) # _Indranil Ghosh_, Mar 21 2017
%Y A280700 Cf. A000120, A001221, A001222, A005187, A279357, A280705, A283475.
%K A280700 nonn
%O A280700 0,3
%A A280700 _Antti Karttunen_, Mar 16 2017