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 A228436 #15 Nov 12 2013 15:47:13 %S A228436 1,3,7,11,15,19,31,41,53,59,63,67,79,83,91,97,103,105,117,127,131,141, %T A228436 157,167,173,179,181,185,193,217,219,223,227,229,237,239,251,255,269, %U A228436 271,277,281,283,291,293,303,307,311,313,317,337,347,351,359,377 %N A228436 Odd n such that n*d are both odious (A000069) or both evil (A001969) for every divisor d of n. %C A228436 A multiplicative analog of A231271. %C A228436 A prime p is a term, iff p and p^2 are both odious or both evil. %H A228436 Peter J. C. Moses, <a href="/A228436/b228436.txt">Table of n, a(n) for n = 1..5000</a> %e A228436 Evil number n=15 has divisors {1,3,5,15}. %e A228436 Since all numbers 15*1=15, 15*3=45, 15*5=75 and 15*15=225 are evil, then 15 is a term. %t A228436 odiousQ[n_]:=OddQ[DigitCount[n,2][[1]]]; selQ[n_]:=OddQ[n] && Length[Union[Map[odiousQ, Map[n #&,Divisors[n]]]]] == 1; Select[Range[400], selQ] (* _Peter J. C. Moses_, Nov 10 2013 *) %o A228436 (PARI) isok(n) = (n % 2) && (!(s = sumdiv(n, d, hammingweight(n*d) % 2)) || (s == numdiv(n))); \\ _Michel Marcus_, Nov 10 2013 %Y A228436 Cf. A231271, A000069, A001969. %K A228436 nonn,base %O A228436 1,2 %A A228436 _Vladimir Shevelev_, Nov 10 2013 %E A228436 More terms from _Michel Marcus_