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a(n) is the n-th prime = -1 (mod n).
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%I #10 Nov 08 2019 11:22:06

%S 2,5,11,19,89,41,181,127,251,199,571,227,1013,433,599,751,2039,593,

%T 2089,859,1637,1429,4001,1103,4049,2053,3779,2267,6263,1499,6571,3583,

%U 5279,3943,6089,2879,11321,4597,7331,4919,15497,3779,15307,6599,8009,7681

%N a(n) is the n-th prime = -1 (mod n).

%C Main diagonal of A093870.

%H Robert Israel, <a href="/A093871/b093871.txt">Table of n, a(n) for n = 1..10000</a>

%p f:= proc(n) local p,count;

%p count:= 0;

%p for p from n-1 by n do

%p if isprime(p) then

%p count:= count+1;

%p if count = n then return p fi

%p fi

%p od;

%p end proc:

%p map(f, [$1..100]); # _Robert Israel_, Nov 08 2019

%Y Cf. A077317, A038700, A093870.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Apr 20 2004

%E Edited and extended by _Franklin T. Adams-Watters_, Aug 29 2006