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A002281
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a(n) = 7(10^n - 1)/9.
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21
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0, 7, 77, 777, 7777, 77777, 777777, 7777777, 77777777, 777777777, 7777777777, 77777777777, 777777777777, 7777777777777, 77777777777777, 777777777777777, 7777777777777777, 77777777777777777, 777777777777777777, 7777777777777777777
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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Ivan Panchenko, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (11,-10).
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FORMULA
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a(n) = 10*a(n-1)+7 with n>0, a(0)=0. - Paolo P. Lava, Jan 23 2009
a(n) = A178634(n) / A002283(n). - Reinhard Zumkeller, May 31 2010
a(n) = a(n-1)+7*10^(n-1) with n>0, a(0)=0; also: a(n) = 11*a(n-1)-10*a(n-2) with n>1, a(0)=0, a(1)=7. - Vincenzo Librandi, Jul 22 2010
G.f.: 7*x/((x-1)*(10*x-1)). - Colin Barker, Jan 24 2013
a(n) = 7*A002275(n). - Wesley Ivan Hurt, Mar 24 2015
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MAPLE
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A002281:=n->7*(10^n-1)/9: seq(A002281(n), n=0..30); # Wesley Ivan Hurt, Mar 24 2015
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MATHEMATICA
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LinearRecurrence[{11, -10}, {0, 7}, 25] (* Robert G. Wilson v, Jul 06 2013 *)
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PROG
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(MAGMA) [7*(10^n-1)/9 : n in [0..30]]; // Wesley Ivan Hurt, Mar 24 2015
(PARI) a(n)=7*(10^n-1)/9 \\ Charles R Greathouse IV, Sep 24 2015
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CROSSREFS
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Cf. A002275, A002276, A002277, A002278, A002279, A002280, A002282, A178630.
Sequence in context: A229281 A144071 A061546 * A097983 A261799 A246236
Adjacent sequences: A002278 A002279 A002280 * A002282 A002283 A002284
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KEYWORD
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easy,nonn
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AUTHOR
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N. J. A. Sloane
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STATUS
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approved
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