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 A078321 #14 Apr 10 2025 05:24:12 %S A078321 1,4,4,6,12,36,20,16,12,100,60,72,64,196,112,20,112,108,180,132,192, %T A078321 384,208,112,36,676,40,260,420,832,432,48,432,1056,612,180,544,1088, %U A078321 760,400,812,1408,720,576,312,2016,768,272,168,332,1300,800,1120,240 %N A078321 Euler's totient of n*rad(n)+1, where rad = A007947 (squarefree kernel). %H A078321 Reinhard Zumkeller, <a href="/A078321/b078321.txt">Table of n, a(n) for n = 1..1000</a> %F A078321 a(n) = A000010(A078310(n)). %t A078321 a[n_] := EulerPhi[1 + n * Times @@ FactorInteger[n][[;;, 1]]]; Array[a, 100] (* _Amiram Eldar_, Apr 10 2025 *) %o A078321 (Haskell) %o A078321 a078321 = a000010 . a078310 -- _Reinhard Zumkeller_, Jul 23 2013 %o A078321 (PARI) a(n) = eulerphi(1 + n * vecprod(factor(n)[, 1])); \\ _Amiram Eldar_, Apr 10 2025 %Y A078321 Cf. A000010, A007947, A078310. %K A078321 nonn,easy %O A078321 1,2 %A A078321 _Reinhard Zumkeller_, Nov 23 2002