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A001535 (10n+1)(10n+9). 1

%I

%S 9,209,609,1209,2009,3009,4209,5609,7209,9009,11009,13209,15609,18209,

%T 21009,24009,27209,30609,34209,38009,42009,46209,50609,55209,60009,

%U 65009,70209,75609,81209,87009,93009,99209,105609,112209,119009,126009,133209,140609

%N (10n+1)(10n+9).

%H T. D. Noe, <a href="/A001535/b001535.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3, -3, 1).

%F a(0)=9, a(1)=209, a(2)=609, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - _Harvey P. Dale_, Oct 15 2014

%F G.f.: (9 + 182*x + 9*x^2)/(1 - x)^3. - _Vincenzo Librandi_, Dec 17 2014

%F E.g.f.: (100*x^2 + 200*x + 9)*exp(x). - _Robert Israel_, Dec 17 2014

%p seq((10*n+1)*(10*n+9),n = 0 .. 100); # _Robert Israel_, Dec 17 2014

%t Times@@@Table[10n+{1,9},{n,0,40}] (* or *) LinearRecurrence[{3,-3,1},{9,209,609},40] (* _Harvey P. Dale_, Oct 15 2014 *)

%t CoefficientList[Series[(9 + 182 x + 9 x^2) / (1 - x)^3, {x, 0, 50}], x] (* _Vincenzo Librandi_, Dec 17 2014 *)

%o (PARI) a(n)=(10*n+1)*(10*n+9) \\ _Charles R Greathouse IV_, Jun 16 2017

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_.

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Last modified April 26 09:52 EDT 2019. Contains 322472 sequences. (Running on oeis4.)