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A181568
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Numbers k such that the largest prime factor of k^2-1 is 101.
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25
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100, 201, 203, 302, 304, 403, 405, 506, 607, 706, 807, 809, 1009, 1011, 1112, 1211, 1312, 1415, 1514, 1516, 1716, 1819, 1918, 2221, 2324, 2524, 2526, 2625, 2627, 3231, 3233, 3334, 3433, 3635, 3736, 3839, 4041, 4241, 4344, 4445, 4544, 4645, 4647, 4746
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OFFSET
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1,1
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COMMENTS
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Sequence is finite, number of terms and last term are still unknown (cf. A175607, A181471).
Are there any terms > 941747621709311?
As k^2 - 1 = (k - 1)(k + 1), a(n) is of the form 101*m +- 1. (End)
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LINKS
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MATHEMATICA
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Select[Range[4746], FactorInteger[#^2-1][[-1, 1]]==101&] (* Metin Sariyar, Sep 15 2019 *)
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PROG
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(Magma) [ n: n in [2..5000] | m eq 101 where m is D[#D] where D is PrimeDivisors(n^2-1) ];
(PARI) is(n)=n=n^2-1; forprime(p=2, 97, n/=p^valuation(n, p)); n>1 && 101^valuation(n, 101)==n \\ Charles R Greathouse IV, Jul 01 2013
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CROSSREFS
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KEYWORD
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fini,nonn
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AUTHOR
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STATUS
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approved
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