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A330825
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Numbers of the form 2^(2^k)*F_k, where F_k is a Fermat prime, A019434.
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1
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OFFSET
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1,1
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COMMENTS
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Also numbers with power-spectral basis {F_n,(F_n-1)^2}. The first element of the power-spectral basis of a(n) is A019434, and the second element is A001146.
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LINKS
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FORMULA
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EXAMPLE
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a(2) = 2^2*(2^2+1) = 20, and the spectral basis of 20 is {5,16}, consisting of primes and powers.
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MAPLE
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F := n -> 2^(2^n)+1;
a := proc(n) if isprime(F(n)) then return 2^(2^n)*F(n) fi; end;
[seq(a(n), n=0..4)];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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