A022459 a(n) = prime(2n+1) mod prime(n).

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, 39, 51, 55, 59, 57, 53, 51, 57, 69, 55, 65, 65, 63, 67, 73, 73, 77, 67, 75, 73, 89, 77, 63, 69, 89, 97, 93, 105, 97, 93, 91, 93, 101, 99, 99, 111, 105, 95, 105, 113, 117

Offset

1,2

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Formula

a(n) = A031368(n+1) modulo A000040(n). - Michel Marcus, Sep 30 2013

For n > 8, a(n) = prime(2n+1) - 2*prime(n). - Charles R Greathouse IV, Sep 30 2013

Mathematica

Table[Mod[Prime[2*n + 1], Prime[n]], {n, 100}] (* T. D. Noe, Sep 30 2013 *)

Prog

(PARI) a(n) = prime(2*n+1) % prime(n); \\ Michel Marcus, Sep 30 2013
(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
(Magma) [NthPrime(2*n+1) mod NthPrime(n): n in [1..50]]; // G. C. Greubel, Feb 28 2018

Crossrefs

Sequence in context: A075097 A138056 A340080 * A060804 A086364 A260662

Adjacent sequences: A022456 A022457 A022458 * A022460 A022461 A022462

Keyword

nonn

Author

Clark Kimberling

Extensions

Missing term a(57) inserted by Michel Marcus, Sep 30 2013

Status

approved