login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

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

%I #8 Mar 10 2021 01:19:00

%S 83,151,167,223,249,257,283,359,373,453,501,563,581,607,669,677,771,

%T 821,849,953,1057,1077,1119,1169,1321,1561,1577,1689,1743,1799,1821,

%U 1981,1987,2017,2031,2463,2513,2573,2611,2833,2859,2869

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

%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="/A256345/b256345.txt">Table of n, a(n) for n = 1..5000</a>

%e See A256342 or A256349.

%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] = 5)

%p else R[x]:= k

%p fi

%p od;

%p end proc:

%p select(filter, [$1..3000]); # _Robert Israel_, Mar 09 2021

%o (PARI) for(i=1,2900,A248218(i)==5&&print1(i","))

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

%K nonn

%O 1,1

%A _M. F. Hasler_, Mar 25 2015