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A256345 Moduli n for which A248218(n) = 5 (length of the terminating cycle of 0 under x -> x^2+1 modulo n).

%I A256345 #8 Mar 10 2021 01:19:00
%S A256345 83,151,167,223,249,257,283,359,373,453,501,563,581,607,669,677,771,
%T A256345 821,849,953,1057,1077,1119,1169,1321,1561,1577,1689,1743,1799,1821,
%U A256345 1981,1987,2017,2031,2463,2513,2573,2611,2833,2859,2869
%N A256345 Moduli n for which A248218(n) = 5 (length of the terminating cycle of 0 under x -> x^2+1 modulo n).
%C A256345 If x is a member and y is a member of this sequence or A248219, then LCM(x,y) is a member. - _Robert Israel_, Mar 09 2021
%H A256345 Robert Israel, <a href="/A256345/b256345.txt">Table of n, a(n) for n = 1..5000</a>
%e A256345 See A256342 or A256349.
%p A256345 filter:= proc(n) local x, k, R,p;
%p A256345   x:= 0; R[0]:= 0;
%p A256345   for k from 1 do
%p A256345     x:= x^2+1 mod n;
%p A256345     if assigned(R[x]) then return evalb(k-R[x] = 5)
%p A256345     else R[x]:= k
%p A256345     fi
%p A256345   od;
%p A256345 end proc:
%p A256345 select(filter, [$1..3000]); # _Robert Israel_, Mar 09 2021
%o A256345 (PARI) for(i=1,2900,A248218(i)==5&&print1(i","))
%Y A256345 Cf. A248218, A248219, A256342 - A256349, A003095, A247981.
%K A256345 nonn
%O A256345 1,1
%A A256345 _M. F. Hasler_, Mar 25 2015