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A056650
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a(n) is the greatest prime factor of a(n-1)^2+a(n-1)+1.
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8
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2, 7, 19, 127, 5419, 1009, 9181, 1423, 96493, 163350799, 25249969, 212520319916977, 784949209969, 145542538757017, 147660435988297, 2508855873622663, 3565137918692593, 6521735641, 11273204227, 16141059763, 125679599753438821, 240780337980146570229319, 7282590063606707136764017
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| Except for the first term the initial (ten at least) terms are one more than a multiple of 6, with the result that a(n)^2+a(n)+1 is in these cases an odd multiple of 3 and appears to be 3 times the product of primes all of which are one more than a multiple of 6.
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LINKS
| Dennis Langdeau, Table of n, a(n) for n = 0..31
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CROSSREFS
| Cf. A031439, A045375.
Sequence in context: A126162 A054423 A137990 * A170869 A162355 A045858
Adjacent sequences: A056647 A056648 A056649 * A056651 A056652 A056653
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KEYWORD
| nonn
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Aug 09 2000
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Nov 26 2001
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