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 A026147 #38 Jan 01 2025 09:49:47
%S A026147 1,4,6,7,10,11,13,16,18,19,21,24,25,28,30,31,34,35,37,40,41,44,46,47,
%T A026147 49,52,54,55,58,59,61,64,66,67,69,72,73,76,78,79,81,84,86,87,90,91,93,
%U A026147 96,97,100,102,103,106,107,109,112,114,115,117,120,121,124,126,127,130
%N A026147 a(n) = position of n-th 1 in A001285 or A010059 (Thue-Morse sequence).
%C A026147 Barbeau notes that if we let A = the first 2^k terms of this sequence and B = the first 2^k terms of A181155, then the two sets A and B have the same sum of powers for first up to the k-th power. I note it holds for 0th power also. - _Michael Somos_, Jun 09 2013
%D A026147 Edward J. Barbeau, Power Play, MAA, 1997. See p. 104.
%H A026147 G. C. Greubel, <a href="/A026147/b026147.txt">Table of n, a(n) for n = 1..10000</a>
%F A026147 a(n) = 1+A001969(n).
%F A026147 a(n) = Sum_{k=0..2n} mod(-2 + Sum_{j=0..k} floor(C(k, j)/2), 3). - _Paul Barry_, Dec 24 2004
%F A026147 a(n) + A010059(n+1) = 2n + 2 for n >= 0. - _Clark Kimberling_, Oct 06 2014
%e A026147 Let k=2. Then A = {1,4,6,7} and B = {2,3,5,8} have the property that 1^0+4^0+6^0+7^0 = 2^0+3^0+5^0+8^0 = 4, 1^1+4^1+6^1+7^1 = 2^1+3^1+5^1+8^1 = 18, and 1^2+4^2+6^2+7^2 = 2^2+3^2+5^2+8^2 = 102. - _Michael Somos_, Jun 09 2013
%t A026147 a[ n_] := If[ n < 1, 0, 2 n + Mod[ Total[ IntegerDigits[ n - 1, 2]], 2] - 1] (* _Michael Somos_, Jun 09 2013 *)
%o A026147 (PARI) a(n)=2*n+hammingweight(n-1)%2-1 \\ _Charles R Greathouse IV_, Mar 22 2013
%o A026147 (PARI) {a(n) = if( n<1, 0, 2*n + subst( Pol( binary( n-1)), x, 1)%2 - 1)} /* _Michael Somos_, Jun 09 2013 */
%o A026147 (Python)
%o A026147 def A026147(n): return 1+((m:=n-1).bit_count()&1)+(m<<1) # _Chai Wah Wu_, Mar 03 2023
%Y A026147 Cf. A001969, A181155.
%K A026147 nonn,easy
%O A026147 1,2
%A A026147 _Clark Kimberling_