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A337630
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Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 7 (mod m), where U(m) and V(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=7 and b=-1, respectively.
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2
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25, 51, 91, 161, 325, 425, 561, 791, 1105, 1633, 1921, 2001, 2465, 2599, 2651, 2737, 7345, 8449, 9361, 10325, 10465, 10825, 11285, 12025, 12291, 13021, 15457, 17111, 18193, 18881, 19307, 20705, 20833, 21931, 24081, 24661, 31521, 32305, 37925, 38801, 39059, 40641
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OFFSET
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1,1
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COMMENTS
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For a,b integers, the following sequences are defined:
generalized Lucas sequences by U(n+2)=a*U(n+1)-b*U(n) and U(0)=0, U(1)=1,
generalized Pell-Lucas sequences by V(n+2)=a*V(n+1)-b*V(n) and V(0)=2, V(1)=a.
These satisfy the identities U(p)^2 == 1 and V(p)==a (mod p) for p prime and b=1,-1.
These numbers may be called weak generalized Lucas-Bruckner pseudoprimes of parameters a and b. The current sequence is defined for a=7 and b=-1.
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LINKS
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MATHEMATICA
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Select[Range[3, 15000, 2], CompositeQ[#] && Divisible[Fibonacci[#, 7]*Fibonacci[#, 7] - 1, #] && Divisible[LucasL[#, 7] - 7, #] &]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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