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A122528
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Minimal number k such that (2k)^(2^n) + 1 is prime, but (2k)^(2^m) + 1 is composite for m<n.
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1
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1, 7, 17, 76, 22, 57, 137, 117, 307, 671, 412, 1279, 767, 35926, 50915, 35453, 24297
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| A079706[a(n)] = 2^n which is the first occurrence of 2^n in A079706. Corresponding primes A084712[a(n)] = {3,197,1336337,284936905588473857,197352587024076973231046657,...} belong to A084712[n] Smallest prime of the form (2n)^k + 1.
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LINKS
| Yves Gallot et al., Generalized Fermat Prime Search
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EXAMPLE
| a(0) = 1 because (2*1)^(2^0) + 1 = 2 + 1 = 3 is prime.
a(1) = 7 because (2*7)^(2^1) + 1 = 14^2 + 1 = 197 is prime but 14 + 1 = 15 is composite.
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CROSSREFS
| Cf. A079706, A084712.
Cf. A056993.
Sequence in context: A120876 A086870 A107693 * A123206 A035078 A177123
Adjacent sequences: A122525 A122526 A122527 * A122529 A122530 A122531
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KEYWORD
| hard,more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 17 2006
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EXTENSIONS
| Definition corrected by T. D. Noe (noe(AT)sspectra.com), May 14 2008
a(9) through a(16) from the extensive tables of generalized Fermat primes compiled by Yves Gallot and others. - T. D. Noe (noe(AT)sspectra.com), May 14 2008
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