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%I #8 Sep 06 2023 21:13:19
%S 3774,6726,10934,11726,12426,13674,15042,16226,17630,17974,18278,
%T 18998,21574,23374,23426,24038,27710,27874,28826,32390,34390,35074,
%U 35126,37630,37774,38170,38626,41210,41426,46342,46774,46990,47874,50518,50806,51794,53074,53846
%N Products k of 4 distinct primes (or tetraprimes) such that none of k-2, k-1, k+1 and k+2 is squarefree.
%e 3772 = 2^2 * 23 * 41, 3773 = 7^3 * 11, 3774 = 2 * 3 * 17 * 37, 3775 = 5^2 * 151, 3776 = 2^6 * 59, so 3774 is a term.
%e 6724 = 2^2 * 41^2, 6725 = 5^2 * 269, 6726 = 2 * 3 * 19 * 59, 6727 = 7 * 31^2, 6728 = 2^3 * 29^2, so 6726 is a term.
%t Select[Range[55000], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1} && !AnyTrue[# + {-2, -1, 1, 2}, SquareFreeQ] &] (* _Amiram Eldar_, Aug 06 2023 *)
%Y Cf. A013929, A046386. Subsequence of A364141.
%K nonn
%O 1,1
%A _Massimo Kofler_, Aug 06 2023