A022457 a(n) = prime(2n) mod prime(n).

1, 1, 3, 5, 7, 11, 9, 15, 15, 13, 17, 15, 19, 21, 19, 25, 21, 29, 29, 31, 35, 35, 33, 45, 35, 37, 45, 49, 53, 55, 39, 49, 43, 59, 51, 57, 59, 57, 63, 63, 63, 71, 61, 71, 69, 81, 69, 57, 67, 83, 91, 91, 95, 91, 87, 87, 81, 99, 93, 97, 107, 97, 87, 97, 107, 109, 95

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A031215, A066066.

Programs

Magma

[NthPrime(2*n) mod NthPrime(n): n in [1..50]]; // G. C. Greubel, Feb 28 2018

Maple

A022457 := proc(n)
    modp(ithprime(2*n),ithprime(n)) ;
end proc:
seq(A022457(n),n=1..67) ; # R. J. Mathar, Sep 02 2016

Mathematica

Table[Mod[Prime[2*n], Prime[n]], {n, 1, 50}] (* G. C. Greubel, Feb 28 2018 *)

PARI

a(n) = prime(2*n) % prime(n); \\ Michel Marcus, Sep 30 2013

Formula

a(n) = A031215(n) modulo A000040(n). - Michel Marcus, Sep 30 2013