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Search: id:A092507
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| A092507 |
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(Smallest prime >= 2^n) + (largest prime <= 2^n). |
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+0
1
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| 2, 4, 8, 18, 30, 68, 128, 258, 508, 1030, 2052, 4092, 8192, 16400, 32792, 65520, 131058, 262172, 524286, 1048596, 2097156, 4194312, 8388620, 16777210, 33554472, 67108860, 134217738, 268435446, 536870858, 1073741832, 2147483616
(list; graph; listen)
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OFFSET
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0,1
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MAPLE
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[seq( (nextprime(2^x)+prevprime(2^x)), x=2..20)];
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MATHEMATICA
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PrevPrim[n_] := Block[{k = n - 1}, While[ !PrimeQ[k], k-- ]; k]; NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; Table[PrevPrim[2^n+1] + NextPrim[2^n-1], {n, 31}] (from Robert G. Wilson v Apr 14 2004)
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CROSSREFS
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Cf. A058249.
Sequence in context: A104879 A156805 A113153 this_sequence A024415 A018096 A110110
Adjacent sequences: A092504 A092505 A092506 this_sequence A092508 A092509 A092510
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KEYWORD
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nonn
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AUTHOR
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Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Apr 05 2004
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 14 2004
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