cp's OEIS Frontend

A263769 Smallest prime q such that q == -1 (mod prime(n)-1).

%I A263769 #16 Nov 20 2015 12:27:37
%S A263769 2,3,3,5,19,11,31,17,43,83,29,71,79,41,137,103,173,59,131,139,71,233,
%T A263769 163,263,191,199,101,211,107,223,251,389,271,137,443,149,311,647,331,
%U A263769 859,1423,179,379,191,587,197,419,443
%N A263769 Smallest prime q such that q == -1 (mod prime(n)-1).
%C A263769 a(n): A000040(1), A065091(1), A002145(1), A007528(1), A030433(1), A068231(1), A127576(1), A061242(1), A141857(1), A141976(1), A132236(1), A142111(1), A142198(1), A141898(1), A141926(1), A142531(1), A142004(1), A142799(1), A142068(1), A142099(1), ...
%C A263769 Smallest prime q such that (prime(n)^2 + q*prime(n))/(prime(n) + 1) is an integer.
%H A263769 Robert Israel, <a href="/A263769/b263769.txt">Table of n, a(n) for n = 1..6000</a>
%e A263769 a(4) = 5 because 5 == -1 (mod prime(4)-1) and is prime.
%p A263769 for n from 1 to 100 do
%p A263769   k:= ithprime(n)-1;
%p A263769   q:= 2;
%p A263769   while (1 + q) mod k <> 0 do
%p A263769     q:= nextprime(q)
%p A263769   od;
%p A263769   A[n]:= q;
%p A263769 od:
%p A263769 seq(A[i],i=1..1000); # _Robert Israel_, Oct 26 2015
%t A263769 Table[q = 2; z = Prime@ n - 1; While[Mod[q, z] != z - 1, q = NextPrime@ q]; q, {n, 59}] (* _Michael De Vlieger_, Oct 26 2015 *)
%Y A263769 Cf. A263730, A263770.
%Y A263769 Cf. A000040, A065091, A002145, A007528, A030433, A068231, A127576, A061242, A141857, A141976, A132236, A142111, A142198, A141898, A141926, A142531, A142004, A142799, A142068, A142099.
%K A263769 nonn
%O A263769 1,1
%A A263769 _Juri-Stepan Gerasimov_, Oct 25 2015
%E A263769 Corrected and edited by _Robert Israel_, Oct 26 2015,