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 A179282 Numbers n such that 2^n-2 and 2^n+2 are not squarefree. 0
 1, 22, 31, 64, 79, 91, 106, 111, 148, 151, 190, 205, 211, 232, 235, 271, 274, 311, 316, 331, 341, 358, 391, 400, 442, 451, 466, 484, 511, 526 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Most (not all) of the terms are of the form: x^2-y^2, for x>y>0. 31=16^2-15^2, 64=10^2-6^2=17^2-15^2, 79=40^2-39^2, 91=10^2-3^2=46^2-45^2, 111=20^2-17^2=56^2-55^2, 148=11^2-3^3=38^2-36^2, 151=76^2-75^2, 205=23^2-18^2=103^2-102^2, 211=106^2-105^2. LINKS EXAMPLE 2^22-2=2*7^2*127*337, 2^22+2=2*3^2*43*5419. MATHEMATICA Select[Range@211, !(SquareFreeQ[2^#-2]||SquareFreeQ[2^#+2])&] CROSSREFS Cf. A005117. Sequence in context: A129073 A092215 A239431 * A106555 A106557 A142347 Adjacent sequences:  A179279 A179280 A179281 * A179283 A179284 A179285 KEYWORD nonn,hard,more AUTHOR Vladimir Joseph Stephan Orlovsky, Mar 22 2011 EXTENSIONS a(14)-a(30) from D. S. McNeil, Mar 23 2011 STATUS approved

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Last modified November 15 11:35 EST 2018. Contains 317238 sequences. (Running on oeis4.)