A095393 - OEIS

%I #4 Oct 15 2013 22:32:25

%S 18,19,25,33,39,42,61,65,85,86,92,100,102,112,154,175,203,259,265,281,

%T 369,380,384,441,495,518,611,649,748,840,1083,1355,1376,1515,1559,

%U 1610,1703,1874,2226,2355,2464,2667,2716,3371,3577,4011,4021,4791,5290,5808

%N Terms n are such that exactly half[=24] of the {210n+r} set is prime. Here r runs through the reduced residue system mod 210 (RRS[210]).

%F In 210n+RRS[210] the number of primes is 24=phi[210]/2.

%e For n=92269 the 24 primes are:

%e {19376491,19376501,19376503,19376507,19376521,19376527,19376543,19376563,

%e 19376569,19376573,19376579,19376597,19376629,19376633,19376639,19376647,

%e 19376653,19376657,19376663,19376671,19376677,19376683,19376689,19376699}

%t {k=0, u=0, ta=Table[0, {256}]}; Do[{m=0};w=k;Do[s=210k+r; s1=210k+r+2; If[PrimeQ[s], m=m+1], {r, 1, 210}]; If[Equal[m, 24], Print[k];ta[[u]]=k;u=u+1], {k, 0, 1000000}]

%Y Cf. A095389-A095392.

%K nonn

%O 1,1

%A _Labos Elemer_, Jun 16 2004