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%I #4 Oct 21 2020 23:07:21
%S 25,51,91,161,265,325,425,561,791,1105,1113,1325,1633,1921,1961,2001,
%T 2465,2599,2651,2737,3445,4081,4505,4929,7345,7685,8449,9361,10325,
%U 10465,10825,11285,11713,12025,12291,13021,15457,17111,18193,18881,18921,19307
%N Odd composite integers m such that A086902(m) == 7 (mod m).
%C If p is a prime, then A086902(p)==7 (mod p).
%C This sequence contains the odd composite integers for which the congruence holds.
%C The generalized Pell-Lucas sequence of integer parameters (a,b) defined by V(m+2)=a*V(m+1)-b*V(m) and V(0)=2, V(1)=a, satisfy the identity V(p)==a (mod p) whenever p is prime and b=-1,1.
%C For a=7, b=-1, V(m) recovers A086902(m).
%D D. Andrica, O. Bagdasar, Recurrent Sequences: Key Results, Applications and Problems. Springer, 2020.
%D D. Andrica, O. Bagdasar, On some new arithmetic properties of the generalized Lucas sequences, Mediterr. J. Math. (to appear, 2021)
%t Select[Range[3, 20000, 2], CompositeQ[#] && Divisible[LucasL[#, 7] - 7, #] &]
%Y Cf. A006497, A005845 (a=1), A330276 (a=2), A335669 (a=3), A335670 (a=4), A335671 (a=5), A338078 (a=6).
%K nonn
%O 1,1
%A _Ovidiu Bagdasar_, Oct 08 2020
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