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 A078313 #12 Apr 26 2017 02:48:26 %S A078313 1,1,2,1,2,1,2,1,2,1,2,1,3,1,2,2,3,1,2,2,3,2,3,2,3,1,2,2,2,2,3,2,3,2, %T A078313 2,2,3,2,2,1,2,2,3,3,2,2,4,1,2,2,2,3,3,2,3,2,3,2,2,1,2,2,2,2,2,1,3,2, %U A078313 2,2,2,1,4,1,2,2,3,2,2,2,2,2,4,1,2,2,3,2,3,2,3,3,3,1,2,1,3,1,3,3,2,2,3,2,3 %N A078313 Number of distinct prime factors of n*rad(n)+1, where rad=A007947 (squarefree kernel). %C A078313 a(n)=A001221(A078310(n)). %H A078313 Reinhard Zumkeller, <a href="/A078313/b078313.txt">Table of n, a(n) for n = 1..10000</a> %t A078313 A078313[n_] := PrimeNu[n*Times @@ FactorInteger[n][[All, 1]] + 1]; Array[A078313, 50] (* _G. C. Greubel_, Apr 25 2017 *) %o A078313 (PARI) a(n)=omega(n*vecprod(factor(n)[,1])+1) \\ _Charles R Greathouse IV_, Jul 09 2013 %o A078313 (Haskell) %o A078313 a078313 = a001221 . a078310 -- _Reinhard Zumkeller_, Jul 23 2013 %Y A078313 Cf. A078314, A078315. %K A078313 nonn %O A078313 1,3 %A A078313 _Reinhard Zumkeller_, Nov 23 2002