Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #3 Sep 21 2005 03:00:00
%S 2,7,19,37,139,151,163,173,181,199,229,397,409,421,491,557,577,593,
%T 601,613,659,809,839,857,881,887,1439,1459,1657,1667,1889,2029,3023,
%U 3863,4283,5261,5297,5437,5479,7853,7873,7901,8263,8291,8297,8353,8521,8597
%N Let a (resp. b,c,d) be number of primes in the range {2..p} that end in 1 (resp. 3,7,9); sequence gives p such that a=d and b=c.
%e E.g. n=19 {2,3,5,7,11,13,17,19}->{2,3,5,7,1,3,7,9}, a=1, b=2, c=2, d=1, b=c and a=d, therefore accept 19.
%Y Cf. A038563.
%K easy,nonn
%O 2,1
%A Author's name lost.