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A098084
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a(n) satisfies P(n) + P(n+1) + a(n) = least prime >= P(n) + P(n+1), where P(i)=i-th prime.
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3
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0, 3, 1, 1, 5, 1, 1, 1, 1, 1, 3, 1, 5, 7, 1, 1, 7, 3, 1, 5, 5, 1, 1, 5, 1, 7, 1, 7, 1, 1, 5, 1, 1, 5, 7, 3, 11, 1, 7, 1, 7, 1, 5, 7, 1, 9, 5, 7, 1, 1, 7, 7, 7, 1, 1, 9, 1, 9, 5, 5, 1, 1, 1, 7, 1, 5, 5, 7, 5, 7, 7, 1, 3, 5, 7, 1, 1, 11, 1, 1, 13, 1, 13, 5, 1, 15, 1, 1, 5, 7, 1, 1, 5, 1, 7, 1, 1, 5, 5, 3, 5, 3, 19
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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P(1) + P(2) = 2 + 3 = 5; least prime >= 5 = 5, so a(1)=0.
P(2) + P(3) = 3 + 5 = 8; least prime > 8 = 11, so a(2) = 11 - 8 = 3.
P(3) + P(4) = 5 + 7 = 12; least prime > 12 = 13, so a(3) = 13 - 12 = 1.
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MAPLE
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P:= [seq(ithprime(i), i=1..200)]:
map(t -> nextprime(t-1)-t, P[1..-2]+P[2..-1]); # Robert Israel, Feb 04 2020
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MATHEMATICA
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f[n_] := Block[{k = 0, p = Prime[n] + Prime[n + 1]}, While[ !PrimeQ[p + k], k++ ]; k]; Table[ f[n], {n, 103}] (* Robert G. Wilson v, Sep 24 2004 *)
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CROSSREFS
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KEYWORD
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easy,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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