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 A364905 Sphenic numbers with no squarefree neighbors. 1
 170, 530, 595, 638, 651, 665, 874, 962, 1015, 1209, 1495, 1551, 1695, 1749, 1826, 1855, 2035, 2255, 2365, 2431, 2451, 2465, 2526, 2674, 2717, 2726, 2737, 2739, 2751, 2755, 2782, 2849, 2874, 3115, 3145, 3178, 3363, 3367, 3451, 3619, 3655, 3689, 3835, 3905, 3970, 4015, 4017, 4047, 4085 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..49. EXAMPLE 169 = 13^2, 170 = 2 * 5 * 17, 171 = 3^2 * 19, so 170 is a term. 529 = 53^2, 530 = 2 * 5 * 53, 531 = 3^2 * 59, so 530 is a term. MATHEMATICA Select[Range[4500], FactorInteger[#][[;; , 2]] == {1, 1, 1} && ! Or @@ SquareFreeQ /@ (# + {-1, 1} ) &] (* Amiram Eldar, Aug 12 2023 *) PROG (PARI) isok(k) = (bigomega(k)==3) && (omega(k)==3) && !issquarefree(k-1) && !issquarefree(k+1); \\ Michel Marcus, Aug 12 2023 CROSSREFS Intersection of A007304 and A281192. Cf. A013929, A364025. Sequence in context: A045153 A045041 A063943 * A362561 A045089 A114078 Adjacent sequences: A364902 A364903 A364904 * A364906 A364907 A364908 KEYWORD nonn AUTHOR Massimo Kofler, Aug 12 2023 STATUS approved

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Last modified September 15 02:04 EDT 2024. Contains 375929 sequences. (Running on oeis4.)