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 A027698 #17 Sep 19 2021 17:51:35 %S A027698 1,4,5,6,8,11,12,13,15,17,18,19,21,22,25,27,28,29,31,32,33,36,37,39, %T A027698 40,41,42,43,44,46,47,48,49,50,51,52,53,54,58,61,63,65,67,73,75,78,80, %U A027698 81,82,83,84,85,86,88,90,93,94,95,98,100,102,103,104,106,107,110,111,112 %N A027698 Numbers k such that the k-th prime has an odd number of 1's in its binary expansion. %H A027698 T. D. Noe, <a href="/A027698/b027698.txt">Table of n, a(n) for n = 1..10000</a> %t A027698 Select[ Range[ 150 ], OddQ[ Length[ Cases[ IntegerDigits[ Prime[ # ], 2 ], 1 ] ] ]& ] %t A027698 Select[Range[200],OddQ[DigitCount[Prime[#],2,1]]&] (* _Harvey P. Dale_, Sep 19 2021 *) %Y A027698 Cf. A027697, A027699, A027700. %K A027698 nonn,easy %O A027698 1,2 %A A027698 _N. J. A. Sloane_ %E A027698 More terms from _Erich Friedman_