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 A078318 #13 Apr 10 2025 05:25:02 %S A078318 3,6,18,13,42,38,93,18,56,102,186,74,324,198,342,48,540,110,546,272, %T A078318 756,588,972,180,312,678,126,528,1266,972,1596,84,1980,1260,1842,256, %U A078318 2484,1842,2286,402,2613,2124,3534,1440,1281,2220,4536,307,660,672 %N A078318 Sum of divisors of n*rad(n)+1, where rad = A007947 (squarefree kernel). %H A078318 Reinhard Zumkeller, <a href="/A078318/b078318.txt">Table of n, a(n) for n = 1..10000</a> %F A078318 a(n) = A000203(A078310(n)). %t A078318 a[n_] := DivisorSigma[1, 1 + n * Times @@ FactorInteger[n][[;;, 1]]]; Array[a, 100] (* _Amiram Eldar_, Apr 10 2025 *) %o A078318 (PARI) rad(n)=vecprod(factor(n)[,1]) %o A078318 a(n)=sigma(n*rad(n)+1) \\ _Charles R Greathouse IV_, Jul 09 2013 %o A078318 (Haskell) %o A078318 a078318 = a000203 . a078310 -- _Reinhard Zumkeller_, Jul 23 2013 %Y A078318 Cf. A000203, A007947, A078310, A078317, A078319, A078320. %K A078318 nonn %O A078318 1,1 %A A078318 _Reinhard Zumkeller_, Nov 23 2002