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A117387
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Prime nearest to 2^n. In case of a tie, choose the smaller.
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7
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2, 2, 3, 7, 17, 31, 61, 127, 257, 509, 1021, 2053, 4093, 8191, 16381, 32771, 65537, 131071, 262147, 524287, 1048573, 2097143, 4194301, 8388617, 16777213, 33554467, 67108859, 134217757, 268435459, 536870909, 1073741827, 2147483647
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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FORMULA
| a(n) = A000079(n) + A059959(n).
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MATHEMATICA
| f[n_] := Block[{k = 0}, While[ !PrimeQ[2^n - k] && !PrimeQ[2^n + k], k++ ]; Min@Select[{2^n - k, 2^n + k}, PrimeQ@# &]]
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CROSSREFS
| Sequence in context: A038075 A032236 A128776 * A113842 A032161 A098738
Adjacent sequences: A117384 A117385 A117386 * A117388 A117389 A117390
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KEYWORD
| nonn
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AUTHOR
| Lekraj Beedassy (blekraj(AT)yahoo.com), Mar 11 2006
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EXTENSIONS
| Edited, corrected and extended by Robert G. Wilson v (rgwv(at)rgwv.com), Mar 14 2006
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