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 A172187 Numbers k such that k and k+1 are squarefree but 2*k+1 is not. 3
 13, 22, 37, 58, 73, 85, 94, 122, 130, 137, 157, 166, 181, 193, 202, 229, 237, 238, 253, 262, 265, 301, 302, 310, 318, 346, 373, 382, 409, 418, 433, 437, 445, 454, 462, 465, 481, 514, 517, 526, 537, 541, 553, 562, 589, 598, 634, 661, 662, 670, 697, 706, 733 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 MATHEMATICA Select[Range[750], And @@ SquareFreeQ /@ {#, # + 1} && !SquareFreeQ[2# + 1] &] (* Amiram Eldar, Mar 22 2020 *) CROSSREFS Complement of A007674 and A172186. Sequence in context: A164504 A162245 A159302 * A164412 A164472 A164446 Adjacent sequences: A172184 A172185 A172186 * A172188 A172189 A172190 KEYWORD nonn AUTHOR Artur Jasinski, Jan 28 2010 STATUS approved

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Last modified December 6 09:02 EST 2023. Contains 367600 sequences. (Running on oeis4.)