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Numbers of the form i*7^j-1 (i=1..6, j >= 0).
9

%I #26 May 05 2024 03:29:04

%S 0,1,2,3,4,5,6,13,20,27,34,41,48,97,146,195,244,293,342,685,1028,1371,

%T 1714,2057,2400,4801,7202,9603,12004,14405,16806,33613,50420,67227,

%U 84034,100841,117648,235297,352946,470595,588244,705893,823542,1647085,2470628,3294171,4117714,4941257

%N Numbers of the form i*7^j-1 (i=1..6, j >= 0).

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,7,-7).

%F G.f.: x^2*(x+1)*(x^2-x+1)*(x^2+x+1) / ((x-1)*(7*x^6-1)). - _Colin Barker_, Feb 01 2013

%t Sort[Flatten[Table[i 7^j-1,{i,1,6},{j,0,7}]]] (* _Harvey P. Dale_, Feb 03 2011 *)

%Y Smallest number whose base b sum of digits is n: A000225 (b=2), A062318 (b=3), A180516 (b=4), A181287 (b=5), A181288 (b=6), this sequence (b=7), A165804 (b=8), A140576 (b=9), A051885 (b=10). - _Jason Kimberley_, Nov 02 2011

%K nonn,easy

%O 1,3

%A _N. J. A. Sloane_, Jan 25 2011