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A002281 a(n) = 7(10^n - 1)/9. 21
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)
OFFSET

0,2

LINKS

Ivan Panchenko, Table of n, a(n) for n = 0..200

Index entries for linear recurrences with constant coefficients, signature (11,-10).

FORMULA

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

MAPLE

A002281:=n->7*(10^n-1)/9: seq(A002281(n), n=0..30); # Wesley Ivan Hurt, Mar 24 2015

MATHEMATICA

LinearRecurrence[{11, -10}, {0, 7}, 25] (* Robert G. Wilson v, Jul 06 2013 *)

PROG

(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

CROSSREFS

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

KEYWORD

easy,nonn

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified November 17 00:08 EST 2019. Contains 329209 sequences. (Running on oeis4.)