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 A171386 The characteristic function of 2 and 3: 1 if n is prime such that either n-1 or n+1 is prime, else 0. 15
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 OFFSET 1,1 COMMENTS A181354(n) + A181376(n) + A181378(n) + A181380(n) + A181384(n) + A181401(n) + A181403(n) + A181405(n) + a(n) = A052268(n). LINKS Index entries for linear recurrences with constant coefficients, signature (1). FORMULA a(n) = A130130(n) - A130130(n-1), for n>0. MATHEMATICA Join[{0, 1, 1}, LinearRecurrence[{1}, {0}, 102]] (* Ray Chandler, Sep 23 2015 *) PROG (PARI) a(n)=n==2||n==3 \\ Charles R Greathouse IV, Sep 24 2015 CROSSREFS Cf. A000007, A010051, A063524. Sequence in context: A072165 A072608 A295304 * A189816 A194685 A182582 Adjacent sequences:  A171383 A171384 A171385 * A171387 A171388 A171389 KEYWORD nonn,easy,less AUTHOR Juri-Stepan Gerasimov, Dec 07 2009 EXTENSIONS Edited by Charles R Greathouse IV, Mar 23 2010 STATUS approved

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Last modified October 22 12:47 EDT 2019. Contains 328318 sequences. (Running on oeis4.)