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A198857
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a(n) = 10*8^n - 1.
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1
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9, 79, 639, 5119, 40959, 327679, 2621439, 20971519, 167772159, 1342177279, 10737418239, 85899345919, 687194767359, 5497558138879, 43980465111039, 351843720888319, 2814749767106559, 22517998136852479, 180143985094819839
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OFFSET
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0,1
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COMMENTS
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The subsequence of primes begins: 79, 5119, 1784059615882449851322857461811868920478433279, no more through a(50). - Jonathan Vos Post, Oct 31 2011
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LINKS
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FORMULA
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a(n) = 8*a(n-1) + 7.
a(n) = 9*a(n-1) - 8*a(n-2), n>1.
G.f.: ( 9-2*x ) / ( (8*x-1)*(x-1) ). - R. J. Mathar, Oct 31 2011
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PROG
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(Magma) [10*8^n-1: n in [0..30]]
(PARI) Vec((9-2*x)/((8*x-1)*(x-1)) + O(x^30)) \\ Michel Marcus, Feb 26 2015
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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