OFFSET
1,1
EXAMPLE
602 = 2 * 7 * 43 and 606 = 2 * 3 * 101 are sphenic numbers; 603 = 3^2 * 67, 604 = 2^2 * 151 and 605 = 5 * 11^2 are 3 consecutive nonsquarefree numbers, so 602 is a term.
1374 = 2 * 3 * 229 and 1378 = 2 * 13 * 53 are sphenic numbers; 1375 = 5^3 * 11, 1376 = 2^5 * 43 and 1377 = 3^4 * 17 are 3 consecutive nonsquarefree numbers, so 1374 is a term.
MATHEMATICA
Select[Partition[Select[Range[30000], FactorInteger[#][[;; , 2]] == {1, 1, 1} &], 2, 1], Differences[#] == {4} && ! Or @@ SquareFreeQ /@ Range[First[#] + 1, Last[#] - 1] &][[;; , 1]] (* Amiram Eldar, Oct 19 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Massimo Kofler, Oct 19 2023
STATUS
approved