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A096453 Primes p such that the number of primes q, 5 <= q < p, congruent to 1 mod 3, is two less than the number of such primes congruent to 2 mod 3. 1
31, 59, 67, 73, 97, 103, 109, 127, 137, 149, 157, 179, 191, 197, 211, 241, 257, 347, 353, 379, 389, 401, 419, 431, 439, 449, 461, 467, 761, 773, 797, 1787, 1801, 1823, 1847, 1867, 1873, 1879, 1901, 3761, 9203, 198479, 198593 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..43.

MAPLE

ct := -2: q:=2: for n from 2 to 20000 do p:=q: q:=ithprime(n): ct:=ct+`if`(p mod 3 = 1, -1, 1): if(ct=2)then printf("%d, ", q): fi: od: # Nathaniel Johnston, Jun 16 2011

MATHEMATICA

npc1Q[n_]:=Module[{tot=PrimePi[n]-3, c}, c=Count[Prime[Range[3, tot+2]], _?(Mod[ #, 3]==1&)]; c==tot/2-1]; Select[Prime[Range[18000]], npc1Q] (* Harvey P. Dale, Aug 22 2013 *)

CROSSREFS

Cf. A096447-A096455.

Sequence in context: A220539 A193362 A293345 * A218794 A218771 A109356

Adjacent sequences:  A096450 A096451 A096452 * A096454 A096455 A096456

KEYWORD

nonn,more

AUTHOR

Yasutoshi Kohmoto, Aug 12 2004

EXTENSIONS

More terms and better definition from Joshua Zucker, May 21 2006

STATUS

approved

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Last modified April 9 23:58 EDT 2020. Contains 333392 sequences. (Running on oeis4.)