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 A076480 #13 Apr 10 2025 05:25:13 %S A076480 2,1,2,3,4,7,6,7,8,11,10,13,12,15,16,15,16,19,18,21,22,23,22,25,24,27, %T A076480 26,29,28,29,30,31,34,35,36,37,36,39,40,41,40,41,42,45,46,47,46,49,48, %U A076480 51,52,53,52,55,56,57,58,59,58,59,60,63,64,63,66,65,66,69,70,69,70,73 %N A076480 a(n) = n + mu(rad(n)), where mu is the Moebius function (A008683) and rad is the squarefree kernel (A007947). %H A076480 Amiram Eldar, <a href="/A076480/b076480.txt">Table of n, a(n) for n = 1..10000</a> %F A076480 a(n) = n + A076479(n) = n + A008683(A007947(n)). %t A076480 a[n_] := n + (-1)^PrimeNu[n]; Array[a, 100] (* _Amiram Eldar_, Apr 10 2025 *) %o A076480 (PARI) a(n)=n+(-1)^omega(n) \\ _Charles R Greathouse IV_, Aug 08 2013 %Y A076480 Cf. A007947, A008683, A076479. %K A076480 nonn,easy %O A076480 1,1 %A A076480 _Reinhard Zumkeller_, Oct 14 2002