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A137169 a(0) = 2; for n>0, a(n) = smallest number m > a(n-1) such that both m-n and m+n are primes. 2
2, 4, 5, 8, 9, 12, 13, 24, 39, 50, 51, 72, 85, 96, 117, 122, 123, 156, 175, 192, 213, 218, 219, 234, 247, 252, 255, 256, 279, 360, 367, 378, 399, 400, 423, 432, 455, 486, 525, 530, 531, 612, 619, 630, 657, 664, 687, 774, 775, 810, 837, 860, 915, 930, 937, 942 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

A variant of A087711. - R. J. Mathar, Apr 09 2008

LINKS

Table of n, a(n) for n=0..55.

EXAMPLE

4-1=3 prime, 4+1=5 prime; 5-2=3, 5+2=7; 8-3=5, 8+3=11; 9-4=5, 9+4=13;

MAPLE

A137169 := proc(n) option remember ; if n = 0 then RETURN(2) ; fi ; for a from A137169(n-1)+1 do if isprime(a-n) and isprime(a+n) then RETURN(a) ; fi ; od: end: seq(A137169(n), n=0..80) ; # R. J. Mathar, Apr 09 2008

MATHEMATICA

s = ""; k = 0; For[i = 2, i < 22^2, If[PrimeQ[i - k] && PrimeQ[i + k], s = s <> ToString[i] <> ", "; k++ ]; i++ ]; Print[s]

CROSSREFS

See A087711 for another version.

Sequence in context: A188072 A296058 A189205 * A348458 A339816 A002541

Adjacent sequences:  A137166 A137167 A137168 * A137170 A137171 A137172

KEYWORD

nonn,easy

AUTHOR

Vladimir Joseph Stephan Orlovsky, Apr 03 2008

EXTENSIONS

More terms from R. J. Mathar, Apr 09 2008

Typo in Mathematica code corrected by Vincenzo Librandi, Jun 15 2013

STATUS

approved

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Last modified May 22 17:42 EDT 2022. Contains 353957 sequences. (Running on oeis4.)