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A180516 Numbers of the form i*4^j-1 (i=1..3, j >= 0). 9


%S 0,1,2,3,7,11,15,31,47,63,127,191,255,511,767,1023,2047,3071,4095,

%T 8191,12287,16383,32767,49151,65535,131071,196607,262143,524287,

%U 786431,1048575,2097151,3145727,4194303,8388607,12582911,16777215,33554431,50331647,67108863,134217727,201326591,268435455,536870911,805306367,1073741823,2147483647,3221225471

%N Numbers of the form i*4^j-1 (i=1..3, j >= 0).

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,4,-4).

%F a(n) = a(n-1)+4*a(n-3)-4*a(n-4). G.f.: x^2*(x^2+x+1) / ((x-1)*(4*x^3-1)). [_Colin Barker_, Feb 01 2013]

%Y Smallest number whose base b sum of digits is n: A000225 (b=2), A062318 (b=3), this sequence (b=4), A181287 (b=5), A181288 (b=6), A181303 (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

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Last modified December 4 15:05 EST 2016. Contains 278750 sequences.