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A156814 a(n) = 225*n^2 + n. 1
226, 902, 2028, 3604, 5630, 8106, 11032, 14408, 18234, 22510, 27236, 32412, 38038, 44114, 50640, 57616, 65042, 72918, 81244, 90020, 99246, 108922, 119048, 129624, 140650, 152126, 164052, 176428, 189254, 202530, 216256, 230432, 245058, 260134 (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*(-226 - 224*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}, {226, 902, 2028}, 50] (* Vincenzo Librandi, Feb 08 2012 *)

PROG

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

(MAGMA) I:=[226, 902, 2028]; [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

Cf. A156840.

Sequence in context: A218040 A158229 A031708 * A251605 A233943 A234155

Adjacent sequences:  A156811 A156812 A156813 * A156815 A156816 A156817

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 16 2009

STATUS

approved

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Last modified May 15 22:33 EDT 2021. Contains 343937 sequences. (Running on oeis4.)