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A331540
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Number of primes of the form k*2^n + 1 with k < 2^n.
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1
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1, 2, 2, 5, 10, 16, 31, 47, 88, 149, 290, 536, 952, 1769, 3280, 6186, 11638, 21901, 41488, 78543, 149662, 284735, 543155, 1040577, 1994339, 3834731, 7373228, 14206331, 27405523, 52941914, 102381148
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OFFSET
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1,2
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COMMENTS
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Both even and odd k are counted. Variant of A134876.
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LINKS
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PROG
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(PARI) a(n) = sum(k=1, 2^n-1, ispseudoprime(k<<n+1))
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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