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%I #19 Nov 24 2023 12:06:25
%S 9,33,55,63,99,119,153,231,385,399,561,649,935,981,1023,1071,1179,
%T 1189,1199,1441,1595,1763,1881,1953,2001,2065,2255,2289,2465,2703,
%U 2751,2849,2871,3519,3599,3655,3927,4059,4081,4187,5015,5151,5559,6061,6119,6215,6273,6431
%N Odd composite integers m such that A006190(m)^2 == 1 (mod m).
%C If p is a prime, then A006190(p)^2 == 1 (mod p).
%C This sequence contains the odd composite integers for which the congruence holds.
%C The generalized Lucas sequence of integer parameters (a,b) defined by U(n+2) = a*U(n+1)-b*U(n) and U(0)=0, U(1)=1, satisfies the identity U^2(p) == 1 (mod p) whenever p is prime and b=-1.
%C For a=3, b=-1, U(n) recovers A006190(n) ("Bronze" Fibonacci numbers).
%D D. Andrica and O. Bagdasar, Recurrent Sequences: Key Results, Applications and Problems. Springer (to appear, 2020).
%H Dorin Andrica and Ovidiu Bagdasar, <a href="https://doi.org/10.3390/math9080838">On Generalized Lucas Pseudoprimality of Level k</a>, Mathematics (2021) Vol. 9, 838.
%H D. Andrica and O. Bagdasar, <a href="https://repository.derby.ac.uk/item/92yqq/on-some-new-arithmetic-properties-of-the-generalized-lucas-sequences">On some new arithmetic properties of the generalized Lucas sequences</a>, preprint for Mediterr. J. Math. 18, 47 (2021).
%t Select[Range[3, 25000, 2], CompositeQ[#] && Divisible[Fibonacci[#, 3]*Fibonacci[#, 3] - 1, #] &]
%Y Cf. A337231 (a=1, odd terms), A337232 (a=1, even terms), A337233 (a=2).
%K nonn
%O 1,1
%A _Ovidiu Bagdasar_, Aug 20 2020