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A235578 Squareful numbers with squareful neighbors. 4
49, 99, 125, 243, 244, 343, 351, 424, 476, 549, 604, 725, 775, 845, 846, 847, 1025, 1251, 1275, 1324, 1376, 1421, 1449, 1520, 1665, 1675, 1681, 1682, 1683, 1849, 1863, 1925, 2008, 2024, 2057, 2107, 2151, 2224, 2276, 2349, 2367, 2524, 2528, 2575, 2645, 2825 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = A070258(n) + 1. - Amiram Eldar, Feb 09 2021
EXAMPLE
243 is in the sequence because 242 = 2 * 11^2, 243 = 3^5, 244 = 2^2 * 61.
244 is also in the sequence because 245 = 5 * 7^2.
But 245 is not in the sequence because 246 = 2 * 3 * 41.
MATHEMATICA
Select[Range@3051, And @@ Not /@ SquareFreeQ /@ {#-1, #, #+1} &] (* Giovanni Resta, Jan 12 2014 *)
Select[Range[2000], Union[MoebiusMu[{# - 1, #, # + 1}]] == {0} &] (* Alonso del Arte, Jan 12 2014 *)
PROG
(PARI) isok(n) = !issquarefree(n) && !issquarefree(n-1) && !issquarefree(n+1); \\ Michel Marcus, Jan 12 2014
CROSSREFS
Subsequence of A013929.
Cf. A001694, A070258, A228649 (squarefree numbers with squarefree neighbors).
Sequence in context: A031484 A260009 A114013 * A161689 A354342 A230653
KEYWORD
nonn
AUTHOR
EXTENSIONS
Terms corrected by Michel Marcus, Jan 12 2014
STATUS
approved

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Last modified February 25 19:44 EST 2024. Contains 370332 sequences. (Running on oeis4.)