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A156813 a(n) = 225*n^2 - n. 2
224, 898, 2022, 3596, 5620, 8094, 11018, 14392, 18216, 22490, 27214, 32388, 38012, 44086, 50610, 57584, 65008, 72882, 81206, 89980, 99204, 108878, 119002, 129576, 140600, 152074, 163998, 176372, 189196, 202470, 216194, 230368, 244992, 260066 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

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

FORMULA

From Vincenzo Librandi, Feb 08 2012: (Start)

900*a(n) + 1 = (450*n - 1)^2.

G.f.: 2*x*(112 + 113*x)/(1-x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). (End)

E.g.f.: x*(224 + 225*x)*exp(x). - G. C. Greubel, Jun 10 2021

MATHEMATICA

LinearRecurrence[{3, -3, 1}, {224, 898, 2022}, 50] (* Vincenzo Librandi, Feb 08 2012 *)

PROG

(PARI) a(n)=225*n^2-n \\ Charles R Greathouse IV, Dec 23 2011

(MAGMA) I:=[224, 898, 2022]; [n le 3 select I[n] else 3*Self(n-1) -3*Self(n-2) +Self(n-3): n in [1..50]]; // Vincenzo Librandi, Feb 08 2012

(Sage) [n*(225*n -1) for n in (1..50)] # G. C. Greubel, Jun 10 2021

CROSSREFS

Cf. A156814.

Sequence in context: A094209 A158227 A061524 * A233875 A233869 A146745

Adjacent sequences:  A156810 A156811 A156812 * A156814 A156815 A156816

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 16 2009

STATUS

approved

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Last modified July 7 02:44 EDT 2022. Contains 355141 sequences. (Running on oeis4.)