%I #19 Sep 08 2022 08:44:46

%S 1,2,2,2,9,2,13,2,21,15,21,23,21,23,33,31,31,35,33,37,45,39,45,49,39,

%T 39,51,55,59,57,53,51,57,69,55,65,65,63,67,73,73,77,67,75,73,89,77,63,

%U 69,89,97,93,105,97,93,91,93,101,99,99,111,105,95,105,113,117

%N a(n) = prime(2n+1) mod prime(n).

%H Charles R Greathouse IV, <a href="/A022459/b022459.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A031368(n+1) modulo A000040(n). - _Michel Marcus_, Sep 30 2013

%F For n > 8, a(n) = prime(2n+1) - 2*prime(n). - _Charles R Greathouse IV_, Sep 30 2013

%t Table[Mod[Prime[2*n + 1], Prime[n]], {n, 100}] (* _T. D. Noe_, Sep 30 2013 *)

%o (PARI) a(n) = prime(2*n+1) % prime(n); \\ _Michel Marcus_, Sep 30 2013

%o (PARI) v=vector(100,i,1);p=2;q=5;for(n=2,#v,q=nextprime(nextprime(q+1) + 1); p=nextprime(p+1);v[n]=q%p); v \\ _Charles R Greathouse IV_, Sep 30 2013

%o (Magma) [NthPrime(2*n+1) mod NthPrime(n): n in [1..50]]; // _G. C. Greubel_, Feb 28 2018

%K nonn

%O 1,2

%A _Clark Kimberling_

%E Missing term a(57) inserted by _Michel Marcus_, Sep 30 2013