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A198856
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a(n) = 9*8^n - 1.
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1
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8, 71, 575, 4607, 36863, 294911, 2359295, 18874367, 150994943, 1207959551, 9663676415, 77309411327, 618475290623, 4947802324991, 39582418599935, 316659348799487, 2533274790395903, 20266198323167231, 162129586585337855
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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: 71, 294911, 18874367, 83010348331692982271, no more through a(30). - 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.
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MATHEMATICA
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CoefficientList[Series[(8 - x)/((1-x) (1 - 8 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 04 2014 *)
LinearRecurrence[{9, -8}, {8, 71}, 20] (* Harvey P. Dale, Aug 26 2020 *)
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PROG
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(Magma) [9*8^n-1: n in [0..30]];
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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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