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 A056650 a(n) is the greatest prime factor of a(n-1)^2+a(n-1)+1. 7
 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; text; internal format)
 OFFSET 0,1 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. LINKS Dennis Langdeau, Table of n, a(n) for n = 0..31 CROSSREFS Cf. A031439, A045375. Sequence in context: A126162 A054423 A137990 * A182169 A170869 A162355 Adjacent sequences: A056647 A056648 A056649 * A056651 A056652 A056653 KEYWORD nonn AUTHOR Henry Bottomley, Aug 09 2000 EXTENSIONS More terms from Vladeta Jovovic, Nov 26 2001 STATUS approved

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Last modified December 3 19:10 EST 2023. Contains 367540 sequences. (Running on oeis4.)