A181303 Numbers of the form i*7^j-1 (i=1..6, j >= 0).

0, 1, 2, 3, 4, 5, 6, 13, 20, 27, 34, 41, 48, 97, 146, 195, 244, 293, 342, 685, 1028, 1371, 1714, 2057, 2400, 4801, 7202, 9603, 12004, 14405, 16806, 33613, 50420, 67227, 84034, 100841, 117648, 235297, 352946, 470595, 588244, 705893, 823542, 1647085, 2470628, 3294171, 4117714, 4941257

Offset: 1

Author

N. J. A. Sloane, Jan 25 2011

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,7,-7).

Crossrefs

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

Programs

Mathematica

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

Formula

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