A343770 - OEIS

%I #7 Apr 30 2021 07:01:31

%S 11,20,22,31,32,49,64,103,110,173,293,454,496,505,589,673,701,772,784,

%T 821,884,979,1039,1292,1711,1988,2236,2266,2662,2701,4804,6772,8641,

%U 8948,13504,23867,40241

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

%e a(5) = 32 is a term because A187129(32) = 261,

%e A185297(32) = 59, and 2*32+(261 mod 59) = 89 is prime.

%p g:= proc(n) local i,L,x,y;

%p   L:= select(t -> isprime(t) and isprime(2*n-t), [2,seq(i,i=3..n,2)]);

%p   x:= convert(L,`+`);

%p   y:= nops(L)*2*n - x;

%p   y mod x

%p end proc:

%p select(n -> isprime(2*n+g(n)), [$2..10000]); # _Robert Israel_, Apr 29 2021

%o (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 isok(k) = isprime(2*k + apq(k)); \\ _Michel Marcus_, Apr 29 2021

%Y Cf. A185297, A187129.

%K nonn,more

%O 1,1

%A _J. M. Bergot_ and _Robert Israel_, Apr 28 2021