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 A080848 #13 May 17 2025 05:46:05
%S A080848 3,2,3,8,5,18,7,16,18,30,11,24,13,42,45,32,17,36,19,40,63,66,23,48,50,
%T A080848 78,54,56,29,30,31,64,99,102,105,72,37,114,117,80,41,42,43,88,90,138,
%U A080848 47,96,98,100,153,104,53,108,165,112,171,174,59,120,61,186,126,128,195,66
%N A080848 a(n) = n*(mu(n)+2), where mu is the Moebius function (A008683).
%H A080848 Antti Karttunen, <a href="/A080848/b080848.txt">Table of n, a(n) for n = 1..10000</a>
%F A080848 n <= a(n) <= 3*n.
%F A080848 Sum_{n>=1} 1/a(n)^2 = (Pi^4 + 46)/(24*Pi^2). - _Amiram Eldar_, May 17 2025
%t A080848 a[n_] := n * (MoebiusMu[n]+2); Array[a, 100] (* _Amiram Eldar_, May 17 2025 *)
%o A080848 (Scheme) (define (A080848 n) (* n (+ 2 (A008683 n)))) ;; _Antti Karttunen_, Jul 26 2017
%o A080848 (PARI) a(n) = n * (moebius(n)+2); \\ _Amiram Eldar_, May 17 2025
%Y A080848 Cf. A008683, A080847, A080849.
%K A080848 nonn,easy
%O A080848 1,1
%A A080848 _Reinhard Zumkeller_, Feb 20 2003