cp's OEIS Frontend

A125729 Numbers whose base 7 representation is 555....5.

%I A125729 #16 Dec 22 2024 09:30:55
%S A125729 0,5,40,285,2000,14005,98040,686285,4804000,33628005,235396040,
%T A125729 1647772285,11534406000,80740842005,565185894040,3956301258285,
%U A125729 27694108808000,193858761656005,1357011331592040,9499079321144285
%N A125729 Numbers whose base 7 representation is 555....5.
%H A125729 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-7).
%F A125729 a(n) = 5*(7^(n-1)-1)/6 = 5*A023000(n-1).
%F A125729 a(n) = 7*a(n-1) + 5 for n > 1. - _Vincenzo Librandi_, Sep 30 2010
%F A125729 G.f.: 5*x^2 / ( (7*x-1)*(x-1) ). - _R. J. Mathar_, Sep 30 2013
%e A125729 Base 7.............decimal
%e A125729 0........................0
%e A125729 5........................5
%e A125729 55......................40
%e A125729 555....................285
%e A125729 5555..................2000
%e A125729 55555................14005
%e A125729 555555...............98040
%e A125729 5555555.............686285
%e A125729 55555555...........4804000
%e A125729 555555555.........33628005
%e A125729 etc....................etc...
%p A125729 seq(5*(7^n-1)/6, n=0..21);
%t A125729 Table[FromDigits[Table[5,n],7],{n,0,19}] (* _James C. McMahon_, Dec 21 2024 *)
%K A125729 easy,nonn
%O A125729 1,2
%A A125729 _Zerinvary Lajos_, Feb 02 2007