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 A338081 Odd composite integers such that A054413(m)^2 == 1 (mod m). 1
 21, 25, 35, 49, 51, 65, 85, 91, 119, 147, 161, 175, 221, 231, 245, 325, 357, 377, 391, 399, 425, 455, 539, 559, 561, 575, 595, 629, 637, 759, 791, 833, 1001, 1105, 1127, 1225, 1247, 1295, 1309, 1495, 1547, 1633, 1763, 1775, 1921, 2001, 2015, 2261, 2275, 2407 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The generalized Lucas sequence of integer parameters (a,b) is defined by U(m+2) = a*U(m+1)-b*U(m) and U(0)=0, U(1)=1. Whenever p is prime and b=-1,1 we have U^2(p) == 1 (mod p). Here we define the odd composite integers for which U^2(m) == 1 (mod m) holds, for a=7, b=-1, where U(m) is A054413(m). REFERENCES D. Andrica, O. Bagdasar, Recurrent Sequences: Key Results, Applications and Problems. Springer, 2020. D. Andrica, O. Bagdasar, On some new arithmetic properties of the generalized Lucas sequences, Mediterr. J. Math. (to appear, 2021) LINKS MATHEMATICA Select[Range[3, 15000, 2], CompositeQ[#] && Divisible[Fibonacci[#, 7]*Fibonacci[#, 7] - 1, #] &] CROSSREFS Cf. A337231 (a=1, odd terms), A337232 (a=1, even terms), A337233 (a=2), A337234 (a=3, odd terms), A337235 (a=3, even terms), A337236 (a=4), A337237 (a=5),  A338081 (a=6). Sequence in context: A276700 A181781 A324551 * A118568 A147049 A219393 Adjacent sequences:  A338078 A338079 A338080 * A338082 A338083 A338084 KEYWORD nonn AUTHOR Ovidiu Bagdasar, Oct 08 2020 STATUS approved

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Last modified May 10 21:08 EDT 2021. Contains 343780 sequences. (Running on oeis4.)