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 A066427 #26 Nov 30 2024 06:24:11 %S A066427 4,9,16,24,25,40,49,54,56,60,72,81,84,88,90,96,104,108,121,126,128, %T A066427 132,135,136,140,150,152,156,160,169,180,184,189,192,198,200,204,220, %U A066427 224,228,232,234,240,248,250,252,256,260,276,288,289,294,296,297,300,306 %N A066427 Numbers with mu = 0 and infinitary MoebiusMu = -1; (sum of binary digits of prime exponents is odd). %C A066427 First differs from A378489 (the intersection of A000028 and A028260) by the inclusion of 72. - _Peter Munn_, Jul 13 2024 %H A066427 Amiram Eldar, <a href="/A066427/b066427.txt">Table of n, a(n) for n = 1..10000</a> %e A066427 54 is in this sequence because its prime decomposition is 2^1 * 3^3, it is not squarefree and the binary digits of "1" and "3" add up to 3, an odd number. %t A066427 iMoebiusMu[ n_ ] := Switch[ MoebiusMu[ n ], 1, 1, -1, -1, 0, If[ OddQ[ Plus@@(DigitCount[ Last[ Transpose[ FactorInteger[ n ] ] ], 2, 1 ]) ], -1, 1 ] ]; Select[ Range[ 400 ], MoebiusMu[ # ]===0 && iMoebiusMu[ # ]===-1 & ] %o A066427 (PARI) is(n)=my(f=factor(n)[,2]); #f && vecmax(f)>1 && vecsum(apply(hammingweight, f))%2 \\ _Charles R Greathouse IV_, Oct 15 2015 %Y A066427 Cf. A008683, A064179, A066428, A378489. %K A066427 easy,nonn %O A066427 1,1 %A A066427 _Wouter Meeussen_, Dec 27 2001