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

%I A022457 #16 Sep 08 2022 08:44:46
%S A022457 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,
%T A022457 37,45,49,53,55,39,49,43,59,51,57,59,57,63,63,63,71,61,71,69,81,69,57,
%U A022457 67,83,91,91,95,91,87,87,81,99,93,97,107,97,87,97,107,109,95
%N A022457 a(n) = prime(2n) mod prime(n).
%H A022457 G. C. Greubel, <a href="/A022457/b022457.txt">Table of n, a(n) for n = 1..10000</a>
%F A022457 a(n) = A031215(n) modulo A000040(n). - _Michel Marcus_, Sep 30 2013
%p A022457 A022457 := proc(n)
%p A022457     modp(ithprime(2*n),ithprime(n)) ;
%p A022457 end proc:
%p A022457 seq(A022457(n),n=1..67) ; # _R. J. Mathar_, Sep 02 2016
%t A022457 Table[Mod[Prime[2*n], Prime[n]], {n, 1, 50}] (* _G. C. Greubel_, Feb 28 2018 *)
%o A022457 (PARI) a(n) = prime(2*n) % prime(n); \\ _Michel Marcus_, Sep 30 2013
%o A022457 (Magma) [NthPrime(2*n) mod NthPrime(n): n in [1..50]]; // _G. C. Greubel_, Feb 28 2018
%Y A022457 Cf. A000040, A031215, A066066.
%K A022457 nonn
%O A022457 1,3
%A A022457 _Clark Kimberling_