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 A125836 Numbers whose base 8 or octal representation is 555555555......5. 1

%I

%S 0,5,45,365,2925,23405,187245,1497965,11983725,95869805,766958445,

%T 6135667565,49085340525,392682724205,3141461793645,25131694349165,

%U 201053554793325,1608428438346605,12867427506772845,102939420054182765

%N Numbers whose base 8 or octal representation is 555555555......5.

%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (9,-8).

%F a(n)=5*(8^(n-1)-1)/7 = 5*A023001(n-1).

%F a(n)=8*a(n-1)+5 (with a(1)=0) [From _Vincenzo Librandi_, Sep 30 2010]

%F G.f. 5*x^2 / ( (8*x-1)*(x-1) ). - _R. J. Mathar_, Sep 30 2013

%e Octal...............decimal

%e 0........................0

%e 5........................5

%e 55......................45

%e 555....................365

%e 5555..................2925

%e 55555................23405

%e 555555..............187245

%e 5555555............1497965

%e 55555555..........11983725

%e 555555555.........95869805

%e 5555555555.......766958445

%e etc. ...............etc.

%p seq(5*(8^n-1)/7, n=0..20);

%K easy,nonn

%O 1,2

%A _Zerinvary Lajos_, Feb 03 2007

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Last modified July 20 05:43 EDT 2019. Contains 325168 sequences. (Running on oeis4.)