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A024088
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a(n) = 8^n - 1.
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17
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0, 7, 63, 511, 4095, 32767, 262143, 2097151, 16777215, 134217727, 1073741823, 8589934591, 68719476735, 549755813887, 4398046511103, 35184372088831, 281474976710655, 2251799813685247, 18014398509481983
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OFFSET
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0,2
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COMMENTS
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Numbers whose base 8 or octal representation is 777777.......7. - Zerinvary Lajos, Feb 03 2007
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LINKS
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FORMULA
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G.f.: 1/(1-8*x) - 1/(1-x).
E.g.f.: exp(8*x) - exp(x). (End)
a(n) = Sum_{i=1..n} 7^i*binomial(n,n-i) for n>0, a(0)=0. - Bruno Berselli, Nov 11 2015
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MATHEMATICA
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8^Range[0, 20]-1 (* or *) LinearRecurrence[{9, -8}, {0, 7}, 20] (* Harvey P. Dale, Jan 04 2017 *)
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PROG
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(Sage) [gaussian_binomial(3*n, 1, 2) for n in range(0, 20)] # Zerinvary Lajos, May 28 2009
(Sage) [stirling_number2(3*n+1, 2) for n in range(0, 20)] # Zerinvary Lajos, Nov 26 2009
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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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