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 A230851 #15 Sep 23 2019 13:28:01 %S A230851 3,5,6,10,12,17,20,23,24,29,33,34,39,40,43,46,48,53,57,58,63,65,66,68, %T A230851 69,71,78,80,83,86,87,89,92,95,96,101,105,106,111,113,114,115,116,117, %U A230851 119,123,125,126,130,132,136,138,139,141,142,145,149,156,160,163,166,171,172,174,177,178,183 %N A230851 Numbers with divisors which are half odious (A000069) and half evil (A001969). %H A230851 Amiram Eldar, <a href="/A230851/b230851.txt">Table of n, a(n) for n = 1..10000</a> %F A230851 Numbers n such that d(n) = 2*A227872(n) where A227872(n) is number of odious divisors of n. %t A230851 aQ[n_] := DivisorSum[n, (-1)^DigitCount[#, 2][[1]] &] == 0; Select[Range[200], aQ] (* _Amiram Eldar_, Sep 23 2019 *) %o A230851 (PARI) is(n)=!sumdiv(n,d,(-1)^hammingweight(d)) \\ _Charles R Greathouse IV_, Oct 31 2013 %Y A230851 Cf. A000069, A001969, A167171, A227872. %K A230851 nonn %O A230851 1,1 %A A230851 _Juri-Stepan Gerasimov_, Oct 31 2013 %E A230851 Corrected by _Charles R Greathouse IV_, Oct 31 2013