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A156813 a(n) = 225*n^2 - n. 1
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

COMMENTS

900*a(n) + 1 = (450*n - 1)^2. - Vincenzo Librandi, Feb 08 2012

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

G.f.: x*(-224 - 226*x)/(x-1)^3. - Vincenzo Librandi, Feb 08 2012

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Vincenzo Librandi, Feb 08 2012

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)+1*Self(n-3): n in [1..50]]; // Vincenzo Librandi, Feb 08 2012

CROSSREFS

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 May 13 19:36 EDT 2021. Contains 343868 sequences. (Running on oeis4.)