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A109278
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Fastest increasing sequence in which a(n) is a prime closest to the sum of all previous terms.
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1
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2, 2, 5, 11, 19, 41, 79, 157, 317, 631, 1259, 2521, 5039, 10079, 20161, 40343, 80669, 161333, 322669, 645329, 1290673, 2581349, 5162681, 10325369, 20650753, 41301493, 82602997, 165205981, 330411959, 660823921, 1321647869, 2643295709
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OFFSET
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1,1
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COMMENTS
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A109277 is the slowest increasing sequence in which a(n) is a prime closest to the sum of all previous terms.
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LINKS
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EXAMPLE
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a(1)=2, sum(1)=2; prime closest to sum is 2, hence a(2)=2, sum(2)=4; there are two primes 3 and 5 closest to sum(2), we choose the largest one, hence a(3)=5, sum(3)=7, etc.
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MATHEMATICA
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s={2}; su=2; Do[If[PrimeQ[su], a=su, pp=PrimePi[su]; prv=Prime[pp]; nxt=Prime[pp+1]; a=If[su-prv<nxt-su, prv, nxt]]; AppendTo[s, a]; Print[a]; su+=a, {i, 42}]; s
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CROSSREFS
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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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