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 A077066 #13 Apr 10 2025 06:53:03 %S A077066 3,2,6,2,6,14,6,10,6,30,2,38,42,22,6,6,30,62,34,6,74,10,42,30,14,102, %T A077066 26,6,110,114,2,66,138,70,30,38,158,82,42,174,30,182,6,194,66,10,106, %U A077066 14,114,230,78,30,22,42,258,66,30,34,278,282,142,42,154,78,314,318,166 %N A077066 Squarefree kernel of prime(n) + 1. %H A077066 Reinhard Zumkeller, <a href="/A077066/b077066.txt">Table of n, a(n) for n = 1..10000</a> %F A077066 a(n) = A007947(A008864(n)). %F A077066 a(A077067(n)) = A077067(n). %e A077066 a(25) = rad(prime(25)+1) = rad(97+1) = rad(2*7^2) = 14. %t A077066 a[n_] := Times @@ FactorInteger[Prime[n] + 1][[;;, 1]]; Array[a, 100] (* _Amiram Eldar_, Apr 10 2025 *) %o A077066 (PARI) a(n)=my(f=factor(prime(n)+1)[,1]); prod(i=1,#f,f[i]) \\ _Charles R Greathouse IV_, Aug 21 2013 %o A077066 (Haskell) %o A077066 a077066 = a007947 . a008864 -- _Reinhard Zumkeller_, Sep 04 2013 %Y A077066 Cf. A007947, A008864, A077063, A077067. %K A077066 nonn,easy %O A077066 1,1 %A A077066 _Reinhard Zumkeller_, Oct 23 2002