login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A001535 a(n) = (10n+1)*(10n+9). 1
9, 209, 609, 1209, 2009, 3009, 4209, 5609, 7209, 9009, 11009, 13209, 15609, 18209, 21009, 24009, 27209, 30609, 34209, 38009, 42009, 46209, 50609, 55209, 60009, 65009, 70209, 75609, 81209, 87009, 93009, 99209, 105609, 112209, 119009, 126009, 133209, 140609 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

T. D. Noe, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3); a(0)=9, a(1)=209, a(2)=609. - Harvey P. Dale, Oct 15 2014

G.f.: (9 + 182*x + 9*x^2)/(1 - x)^3. - Vincenzo Librandi, Dec 17 2014

E.g.f.: (100*x^2 + 200*x + 9)*exp(x). - Robert Israel, Dec 17 2014

MAPLE

seq((10*n+1)*(10*n+9), n = 0 .. 100); # Robert Israel, Dec 17 2014

MATHEMATICA

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

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

PROG

(PARI) a(n)=(10*n+1)*(10*n+9) \\ Charles R Greathouse IV, Jun 16 2017

CROSSREFS

Sequence in context: A266483 A203364 A218887 * A300136 A274672 A122399

Adjacent sequences:  A001532 A001533 A001534 * A001536 A001537 A001538

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 2 19:31 EDT 2022. Contains 357228 sequences. (Running on oeis4.)