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A080849 a(n) = (mu(n)+2)*n^2, where mu is the Moebius function (A008683).

%I A080849 #15 May 17 2025 05:47:54
%S A080849 3,4,9,32,25,108,49,128,162,300,121,288,169,588,675,512,289,648,361,
%T A080849 800,1323,1452,529,1152,1250,2028,1458,1568,841,900,961,2048,3267,
%U A080849 3468,3675,2592,1369,4332,4563,3200,1681,1764,1849,3872,4050,6348,2209,4608,4802
%N A080849 a(n) = (mu(n)+2)*n^2, where mu is the Moebius function (A008683).
%H A080849 Antti Karttunen, <a href="/A080849/b080849.txt">Table of n, a(n) for n = 1..5000</a>
%F A080849 n^2 <= a(n) <= 3*n^2.
%F A080849 a(n) = n * A080848(n) = A000290(n) * A080847(n). - _Antti Karttunen_, Jul 26 2017
%F A080849 Sum_{n>=1} 1/a(n) = (Pi^4 + 6)/(12*Pi^2). - _Amiram Eldar_, May 17 2025
%t A080849 Table[(MoebiusMu[n]+2)n^2,{n,50}] (* _Harvey P. Dale_, Sep 02 2024 *)
%o A080849 (Scheme) (define (A080849 n) (* n n (+ 2 (A008683 n)))) ;; _Antti Karttunen_, Jul 26 2017
%o A080849 (PARI) a(n) = (moebius(n)+2)*n^2; \\ _Amiram Eldar_, May 17 2025
%Y A080849 Cf. A000290, A008683, A080847, A080848.
%K A080849 nonn,easy
%O A080849 1,1
%A A080849 _Reinhard Zumkeller_, Feb 20 2003