A256347 - OEIS

%I #7 Mar 10 2021 01:19:29

%S 41,123,131,287,317,393,503,547,727,779,861,917,951,1091,1237,1271,

%T 1277,1509,1517,1627,1637,1641,1681,1763,2089,2181,2219,2239,2337,

%U 2357,2383,2489,2531,2671,2751,2789

%N Moduli n for which A248218(n) = 7.

%C 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 Robert Israel, <a href="/A256347/b256347.txt">Table of n, a(n) for n = 1..4000</a>

%p filter:= proc(n) local x, k, R,p;

%p   x:= 0; R[0]:= 0;

%p   for k from 1 do

%p     x:= x^2+1 mod n;

%p     if assigned(R[x]) then return evalb(k-R[x] = 7)

%p     else R[x]:= k

%p     fi

%p   od;

%p end proc:

%p select(filter, [$1..10000]); # _Robert Israel_, Mar 09 2021

%o (PARI) for(i=1,3000,A248218(i)==7&&print1(i","))

%Y Cf. A248218, A248219, A256342 - A256349, A003095, A247981.

%K nonn

%O 1,1

%A _M. F. Hasler_, Mar 25 2015