A065312 - OEIS

%I #18 Jul 02 2018 03:12:54

%S 7,11,19,23,37,41,47,53,59,61,73,79,83,89,101,103,113,127,137,139,149,

%T 151,163,167,173,179,193,197,199,211,227,229,241,251,257,263,271,277,

%U 283,293,307,311,317,331,337,347,349,353,367,373,389,397,419,421,433

%N Primes which occur exactly once in A065308 (prime(n - pi(n))).

%C In A065308 each odd prime seems to appear once or twice. Prime 2 arises there 3 times.

%H Harry J. Smith, <a href="/A065312/b065312.txt">Table of n, a(n) for n = 1..1000</a>

%t With[{s = Array[Prime[# - PrimePi[#]] &, 120]}, Most@ Select[Split[s], Length@ # == 1 &][[All, 1]] ] (* _Michael De Vlieger_, Jun 19 2018 *)

%o (PARI) { n=0; p=1; f=2; m=1; for (i=1, 10^9, a=0; p=nextprime(p + 1); while (p==f, a++; m++; f=prime(m - primepi(m))); if (a==1, write("b065312.txt", n++, " ", p); if (n==1000, return)) ) } \\ _Harry J. Smith_, Oct 16 2009

%Y Cf. A000040, A000720, A054546, A065308, A065309, A065310, A065311.

%K nonn

%O 1,1

%A _Labos Elemer_, Oct 29 2001