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A158406 a(n) = 900*n^2 + 2*n. 2
902, 3604, 8106, 14408, 22510, 32412, 44114, 57616, 72918, 90020, 108922, 129624, 152126, 176428, 202530, 230432, 260134, 291636, 324938, 360040, 396942, 435644, 476146, 518448, 562550, 608452, 656154, 705656, 756958, 810060, 864962, 921664 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The identity (900*n + 1)^2 - (900*n^2 + 2*n)*30^2 = 1 can be written as A158407(n)^2 - a(n)*30^2 = 1. - Vincenzo Librandi, Feb 09 2012

LINKS

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

Vincenzo Librandi, X^2-AY^2=1

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

FORMULA

G.f.: x*(-902 - 898*x)/(x-1)^3. - Vincenzo Librandi, Feb 09 2012

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Vincenzo Librandi, Feb 09 2012

MATHEMATICA

LinearRecurrence[{3, -3, 1}, {902, 3604, 8106}, 50] (* Vincenzo Librandi, Feb 09 2012 *)

PROG

(MAGMA) I:=[902, 3604, 8106]; [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 09 2012

(PARI) for(n=1, 40, print1(900*n^2 + 2*n", ")); \\ Vincenzo Librandi, Feb 09 2012

CROSSREFS

Cf. A158407.

Sequence in context: A268585 A224611 A031528 * A323143 A284744 A111042

Adjacent sequences:  A158403 A158404 A158405 * A158407 A158408 A158409

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Mar 18 2009

STATUS

approved

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Last modified February 18 15:04 EST 2020. Contains 332019 sequences. (Running on oeis4.)