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Search: id:A051728
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| A051728 |
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Smallest number at distance 2n from nearest prime. |
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+0
21
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| 2, 0, 23, 53, 409, 293, 211, 1341, 1343, 2179, 3967, 15705, 16033, 19635, 31425, 24281, 31429, 31431, 31433, 155959, 38501, 58831, 203713, 268343, 206699, 370311, 370313, 370315, 370317, 1349591, 1357261, 1272749, 1357265, 1357267
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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a(0) = 2. For n > 0, let f(m) = minimal distance from m to closest prime (excluding m itself). The a(n) = min { m : f(m) = 2n }.
f(m) is tabulated in A051700. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 18 2007
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MAPLE
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A051700 := proc(m) if m <= 2 then op(m+1, [2, 1, 1]) ; else min(nextprime(m)-m, m-prevprime(m)) ; fi ; end: A051728 := proc(n) local m ; if n = 0 then RETURN(2); else for m from 0 do if A051700(m) = 2 * n then RETURN(m) ; fi ; od: fi ; end: seq(A051728(n), n=0..20) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 18 2007
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CROSSREFS
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Related sequences: A023186-A023188, A046929-A046931, A051650, A051652, A051697-A051702, A051728-A051730.
Cf. A132470.
Sequence in context: A106708 A138551 A133490 this_sequence A005359 A008842 A130915
Adjacent sequences: A051725 A051726 A051727 this_sequence A051729 A051730 A051731
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KEYWORD
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nonn,easy,nice
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AUTHOR
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njas
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Dec 07 1999
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