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 A072581 #11 Jul 28 2025 03:11:38
%S A072581 19,53,139,193,311,313,409,577,641,719,787,809,1033,1061,1097,1171,
%T A072581 1193,1289,1627,1637,1657,1669,1693,1699,1747,1811,1877,1889,2083,
%U A072581 2089,2153,2161,2179,2203,2213,2273,2311,2659,2689,2753,3169,3677,3727,3733
%N A072581 a(n) = A000040(A072578(n)).
%H A072581 Amiram Eldar, <a href="/A072581/b072581.txt">Table of n, a(n) for n = 1..10000</a>
%F A072581 A000120(a(n)) = A023416(A072578(n)) = A014499(n).
%e A072581 In binary representation 80 = '1010000' has five 0's and A000040(80) = 409 = '110011001' has five 1's: therefore 409 is a term.
%t A072581 With[{m = 600}, Select[Transpose[{Range[m], Prime[Range[m]]}], DigitCount[First[#], 2, 0] == DigitCount[Last[#], 2, 1] &]][[;; , 2]] (* _Amiram Eldar_, Jul 28 2025 *)
%Y A072581 Cf. A000040, A000120, A014499, A023416, A072439, A072578, A072580, A072582, A072584.
%K A072581 nonn,base,easy
%O A072581 1,1
%A A072581 _Reinhard Zumkeller_, Jun 23 2002