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Search: id:A159260
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| A159260 |
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Numbers n such that 1 + sum_{i=1..n} 2^prime[i] is prime. |
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2
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OFFSET
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1,2
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COMMENT
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See A159261 for the primes produced by these n. See A159262 for prime(n), the largest exponent in the sum. The term 1903 produces a probable prime; smaller n produce provable primes. See A122035 for the reducibility of the polynomial obtained by replacing 2 by x.
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EXAMPLE
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1 is here because 1 + 2^2 = 5 is prime.
2 is here because 1 + 2^2 + 2^3 = 13 is prime.
4 is here because 1 + 2^2 + 2^3 + 2^5 + 2^7 = 173 is prime.
5 is here because 1 + 2^2 + 2^3 + 2^5 + 2^7 + 2^11 = 2111 is prime.
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MATHEMATICA
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s=1; Reap[Do[s=s+2^Prime[n]; If[PrimeQ[s], Sow[n]], {n, 2000}]][[2, 1]]
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CROSSREFS
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Sequence in context: A097684 A092752 A152603 this_sequence A013103 A012973 A013154
Adjacent sequences: A159257 A159258 A159259 this_sequence A159261 A159262 A159263
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Apr 07 2009
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