cp's OEIS Frontend

A343770 Numbers k such that 2*k+(A187129(k) mod A185297(k)) is prime.

%I A343770 #7 Apr 30 2021 07:01:31
%S A343770 11,20,22,31,32,49,64,103,110,173,293,454,496,505,589,673,701,772,784,
%T A343770 821,884,979,1039,1292,1711,1988,2236,2266,2662,2701,4804,6772,8641,
%U A343770 8948,13504,23867,40241
%N A343770 Numbers k such that 2*k+(A187129(k) mod A185297(k)) is prime.
%e A343770 a(5) = 32 is a term because A187129(32) = 261,
%e A343770 A185297(32) = 59, and 2*32+(261 mod 59) = 89 is prime.
%p A343770 g:= proc(n) local i,L,x,y;
%p A343770   L:= select(t -> isprime(t) and isprime(2*n-t), [2,seq(i,i=3..n,2)]);
%p A343770   x:= convert(L,`+`);
%p A343770   y:= nops(L)*2*n - x;
%p A343770   y mod x
%p A343770 end proc:
%p A343770 select(n -> isprime(2*n+g(n)), [$2..10000]); # _Robert Israel_, Apr 29 2021
%o A343770 (PARI) apq(n) = my(s=0, t=0); forprime(p=1, n, if (isprime(2*n-p), s += p; t+= 2*n-p)); t % s;
%o A343770 isok(k) = isprime(2*k + apq(k)); \\ _Michel Marcus_, Apr 29 2021
%Y A343770 Cf. A185297, A187129.
%K A343770 nonn,more
%O A343770 1,1
%A A343770 _J. M. Bergot_ and _Robert Israel_, Apr 28 2021