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 A152580 a(n) = 7^(2^n) + 2. 1
 9, 51, 2403, 5764803, 33232930569603, 1104427674243920646305299203 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS These numbers are divisible by 3. This follows by expanding the binomial (6+1)^(2^n) + 2 to get 6h + 1 + 2 for some h. Therefore 3 divides 7^(2^n) + 2. LINKS FORMULA a(n) = A165425(n+3) + 2. - R. J. Mathar, Sep 10 2016 MAPLE A152580:=n->7^(2^n) + 2: seq(A152580(n), n=0..8); # Wesley Ivan Hurt, Jan 22 2017 PROG (PARI) g(a, n) = if(a%2, b=2, b=1); for(x=0, n, y=a^(2^x)+b; print1(y", ")) (PARI) a(n) = 7^(2^n) + 2; \\ Michel Marcus, Jan 24 2017 CROSSREFS Cf. A165425. Sequence in context: A272393 A231748 A181161 * A197722 A172470 A120665 Adjacent sequences:  A152577 A152578 A152579 * A152581 A152582 A152583 KEYWORD nonn,easy AUTHOR Cino Hilliard, Dec 08 2008 STATUS approved

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Last modified April 9 10:52 EDT 2020. Contains 333348 sequences. (Running on oeis4.)