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A121171
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Largest prime divisor of Lucas(5*n), where Lucas(k) = A000032(k).
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5
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11, 41, 31, 2161, 151, 2521, 911, 3041, 541, 570601, 39161, 20641, 24571, 12317523121, 18451, 23725145626561, 12760031, 10783342081, 87382901, 5738108801, 767131, 59996854928656801, 686551, 23735900452321, 28143378001, 42426476041450801, 119611
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OFFSET
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1,1
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COMMENTS
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Final digit of a(n) is 1. Mod[a(n),10] = 1. Final digit of many prime divisors of Lucas(5*n) is 1.
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LINKS
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FORMULA
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MATHEMATICA
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Table[Max[Flatten[FactorInteger[Fibonacci[5n-1]+Fibonacci[5n+1]]]], {n, 1, 40}]
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PROG
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(PARI)
lucas(n) = fibonacci(n+1)+fibonacci(n-1); \\ A000032
a(n) = vecmax(factor(lucas(5*n))[, 1]); \\ Daniel Suteu, May 26 2022
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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