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 A140707 #14 Apr 08 2020 00:09:29
%S A140707 1,2,5,10,11,12,13,21,22,23,26,27,28,29,39,42,45,46,47,51,54,57,58,59,
%T A140707 61,78,87,90,91,93,94,102,105,114,115,117,118,120,122,124,125,159,174,
%U A140707 175,182,183,186,187,189,191,207,210,215,219,220,221,223,230,234,235
%N A140707 A positive integer n is included if n written in binary contains the same number of 0's as the number of distinct primes that divide n.
%H A140707 Carl R. White, <a href="/A140707/b140707.txt">Table of n, a(n) for n = 1..10000</a>
%F A140707 {n: A080791(n) = A001221(n)}. - _R. J. Mathar_, Aug 08 2008
%e A140707 90 written in binary is 1011010. There are three 0's in this binary representation. 90 has the prime factorization: 2^1 *3^2 *5^1. There are 3 distinct primes dividing 90. Since the number of 0's in the binary representation equals the number of distinct primes dividing 90, then 90 is in the sequence.
%p A140707 A080791 := proc(n) local dgs ; dgs := convert(n,base,2) ; nops(dgs)-add(i,i=dgs) ; end: A001221 := proc(n) nops(numtheory[factorset](n)) ; end: isA140707 := proc(n) RETURN( A080791(n) = A001221(n)) ; end: for n from 1 to 300 do if isA140707(n) then printf("%d,",n) ; fi; od: # _R. J. Mathar_, Aug 08 2008
%t A140707 Select[Range[300],DigitCount[#,2,0]==PrimeNu[#]&] (* _Harvey P. Dale_, Dec 08 2017 *)
%Y A140707 Cf. A071594, A001221, A023416.
%K A140707 base,nonn
%O A140707 1,2
%A A140707 _Leroy Quet_, Jul 11 2008
%E A140707 Extended beyond 42 by _R. J. Mathar_, Aug 08 2008