A364141 Products k of 4 distinct primes (or tetraprimes) such that k has no squarefree neighbors.

3774, 5565, 6726, 8151, 10659, 10934, 11726, 11935, 12426, 13035, 13195, 13674, 13755, 14763, 15042, 15249, 15351, 15785, 16215, 16226, 17630, 17765, 17974, 17985, 18249, 18278, 18915, 18998, 19565, 20085, 21385, 21574, 21855, 22015, 23023, 23345, 23374, 23426, 24038, 24605, 25185

Offset: 1

Author

Massimo Kofler, Jul 10 2023

Keywords

• nonn

Examples

			3773 = 7^3 * 11, 3774 = 2 * 3 * 17 * 37, 3775 = 5^2 * 151, so 3774 is a term.
5564 = 2^2 * 13 * 107, 5565 = 3 * 5 * 7 * 53, 5566 = 2 * 11^2 * 23, so 5565 is a term.
		

Crossrefs

Cf. A013929, A046386.

Programs

Mathematica

Select[Range[26000], FactorInteger[#][[;; , 2]] == {1, 1, 1, 1} && ! SquareFreeQ[# - 1] && ! SquareFreeQ[# + 1] &] (* Amiram Eldar, Jul 10 2023 *)