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A167771
Twice-isolated primes: primes p such that neither p+-2 nor p+-4 is prime.
4
2, 53, 89, 157, 173, 211, 251, 257, 263, 293, 331, 337, 359, 367, 373, 389, 409, 449, 479, 509, 541, 547, 557, 563, 577, 587, 593, 607, 631, 653, 683, 691, 701, 709, 719, 727, 733, 751, 787, 797, 839, 919, 929, 947, 953, 977, 983, 991, 997, 1039, 1069, 1103
OFFSET
1,1
COMMENTS
2 together with primes p with property that (p-previous prime)>=6 and (next prime-p)>=6.
By the finitude of the generalized Brun constants, this sequence includes almost all primes.
LINKS
EXAMPLE
a(1)=2 (-2,0,4,6 are nonprimes); a(2)=53 (49,51,55,57 are nonprimes).
MATHEMATICA
Join[{2}, Select[Prime[Range[200]], NoneTrue[#+{4, 2, -2, -4}, PrimeQ]&]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 21 2016 *)
CROSSREFS
Sequence in context: A200087 A346215 A139841 * A062853 A059703 A212889
KEYWORD
nonn
AUTHOR
EXTENSIONS
Comment from Charles R Greathouse IV, Nov 12 2009
STATUS
approved