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A051652 Smallest number at distance n from nearest prime. 18
2, 1, 0, 26, 23, 118, 53, 120, 409, 532, 293, 1140, 211, 1340, 1341, 1342, 1343, 1344, 2179, 15702, 3967, 15704, 15705, 19632, 16033, 19634, 19635, 31424, 31425, 31426, 24281, 31428, 31429, 31430, 31431, 31432, 31433, 155958, 155959, 155960, 38501 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

R. J. Mathar, Table of n, a(n) for n=0..80.

MAPLE

A051700 := proc(m) option remember ; if m <= 2 then op(m+1, [2, 1, 1]) ; else min(nextprime(m)-m, m-prevprime(m)) ; fi ; end:

A051652 := proc(n) local m ; if n = 0 then RETURN(2); else for m from 0 do if A051700(m) = n then RETURN(m) ; fi ; od: fi ; end:

for n from 0 to 79 do printf("%d %d\n", n, A051652(n)); od: # R. J. Mathar, Jul 22 2009

MATHEMATICA

A051700[n_] := A051700[n] = Min[ NextPrime[n] - n, n - NextPrime[n, -1]]; a[n_] := For[m = 0, True, m++, If[A051700[m] == n, Return[m]]]; a[0] = 2; Table[ a[n], {n, 0, 40}] (* Jean-Fran├žois Alcover, Dec 19 2011, after R. J. Mathar *)

Join[{2, 1, 0}, Drop[Flatten[Table[Position[Table[Min[NextPrime[n]-n, n-NextPrime[ n, -1]], {n, 200000}], _?(#==i&), {1}, 1], {i, 40}]], 2]] (* Harvey P. Dale, Mar 16 2015 *)

CROSSREFS

Related sequences: A023186-A023188, A046929-A046931, A051650, A051652, A051697-A051702, A051728-A051730.

Sequence in context: A202697 A268436 A249570 * A077019 A139037 A108511

Adjacent sequences:  A051649 A051650 A051651 * A051653 A051654 A051655

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from James A. Sellers, Dec 07 1999

STATUS

approved

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Last modified July 21 02:57 EDT 2017. Contains 289629 sequences.