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%I #18 Jan 31 2021 08:14:27
%S 3,2,6,6,30,42,6,30,66,210,30,114,210,462,138,78,870,930,1122,210,222,
%T 390,1722,330,42,510,1326,318,330,798,42,4290,2346,4830,1110,570,6162,
%U 246,3486,7482,2670,2730,570,582,462,330,11130,1554,12882,13110,2262,3570,330,210,258,8646,2010
%N a(n) = product of distinct primes dividing prime(n)^2 - 1.
%H Amiram Eldar, <a href="/A275630/b275630.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A007947(A084920(n)). - _Michel Marcus_, Jan 30 2021
%F a(n) = A077063(n)*A077066(n)/2, for n > 1. - _Amiram Eldar_, Jan 30 2021
%t a[n_] := Times @@ FactorInteger[Prime[n]^2 - 1][[;; , 1]]; Array[a, 60] (* _Amiram Eldar_, Jan 30 2021 *)
%o (PARI) a(n) = factorback(factorint(prime(n)^2-1)[, 1]); \\ _Michel Marcus_, Jan 30 2021
%Y Subsequence of A007947.
%Y Cf. A077063, A077066, A084920.
%K nonn
%O 1,1
%A _N. J. A. Sloane_, Aug 07 2016