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A340128 a(n) = (n*prime(n)) mod prime(n+1).

%I A340128 #38 Jan 21 2021 11:57:00
%S A340128 2,1,1,6,3,10,5,14,4,11,8,34,17,38,16,22,27,26,66,33,32,78,40,2,1,51,
%T A340128 106,53,110,88,7,82,73,107,81,98,104,15,112,118,99,153,107,21,109,81,
%U A340128 105,35,131,33,172,137,223,190,196,202,157,206,45,163,269,53
%N A340128 a(n) = (n*prime(n)) mod prime(n+1).
%H A340128 Seiichi Manyama, <a href="/A340128/b340128.txt">Table of n, a(n) for n = 1..10000</a>
%e A340128 a(1) = (prime(1) * 1) mod prime(1+1) =  2 * 1 mod  3 = 2,
%e A340128 a(2) = (prime(2) * 2) mod prime(2+1) =  3 * 2 mod  5 = 1,
%e A340128 a(3) = (prime(3) * 3) mod prime(3+1) =  5 * 3 mod  7 = 1,
%e A340128 a(4) = (prime(4) * 4) mod prime(4+1) =  7 * 4 mod 11 = 6,
%e A340128 a(5) = (prime(5) * 5) mod prime(5+1) = 11 * 5 mod 13 = 3.
%t A340128 Table[Mod[n*Prime[n],Prime[n+1]],{n,62}] (* _Stefano Spezia_, Jan 17 2021 *)
%o A340128 (Ruby) require 'prime'
%o A340128 values = []
%o A340128 primes = Prime.first(20)
%o A340128 primes.each_index do |n|
%o A340128     next if n < 1
%o A340128     values << (primes[n-1] * n) % primes[n]
%o A340128 end
%o A340128 p values
%o A340128 (PARI) a(n) = (prime(n)*n) % prime(n+1); \\ _Michel Marcus_, Jan 20 2021
%Y A340128 Cf. A000040, A033286, A340649.
%K A340128 nonn,look
%O A340128 1,1
%A A340128 _Simon Strandgaard_, Jan 15 2021