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A123646
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Smallest generalized Fermat prime of the form a^(2^n) + b^(2^n), where bases a,b>1; or -1 if no such prime exists.
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0
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5, 13, 97, 2070241, 4338014017, 3512911982806776822251393039617, 4457915690803004131256192897205630962697827851093882159977969339137, 1638935311392320153195136107636665419978585455388636669548298482694235538906271958706896595665141002450684974003603106305516970574177405212679151205373697500164072550932748470956551681
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OFFSET
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0,1
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LINKS
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MATHEMATICA
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Do[f=Min[Select[Take[Union[ Flatten[ Table[ i^(2^n) + j^(2^n), {i, 2, 300}, {j, 2, 300} ] ] ], 500], PrimeQ]]; Print[{n, f}], {n, 0, 7}]
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CROSSREFS
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Cf. A000215 (Fermat numbers: 2^(2^n) + 1), A019434 (Fermat primes of the form 2^(2^n) + 1).
Cf. A111635 (allows one of a,b to be 1).
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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