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A176815
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Radius of the second-shortest interval (of positive length) centered at prime(n) that has prime endpoints, (zero if no solution exists).
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0
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0, 0, 0, 0, 8, 10, 12, 0, 18, 18, 28, 24, 18, 30, 24, 30, 30, 42, 30, 18, 30, 48, 30, 42, 54, 30, 24, 24, 42, 54, 30, 42, 36, 42, 42, 42, 54, 60, 60, 24, 48, 30, 60, 36, 60, 72, 18, 84, 36, 78, 36, 42, 42, 18, 24, 30, 42, 60, 36, 30, 84, 54, 30, 48, 84, 66, 48, 60, 54, 72, 36
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OFFSET
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1,5
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COMMENTS
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7+-10->primes;but 7-10=-3,so,term #4(for number 7) is 0, 11+-8->primes, 13+-10->primes, 17+-12->primes, 19+-22->primes;but 19-22=-3,so,term #8(for number 19)is 0, 23+-18->primes,..
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LINKS
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MATHEMATICA
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f[n_]:=Module[{a=1}, While[ !PrimeQ[n-a]||!PrimeQ[n+a], a++ ]; r[n, ++a]]; r[n_, k_]:=Module[{a=k}, While[ !PrimeQ[n-a]||!PrimeQ[n+a], a++ ]; If[a>n, 0, a]]; Table[f[Prime[n]], {n, 1, 5!}]
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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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