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A154360 a(n) = 250*n - 180. 5
-180, 70, 320, 570, 820, 1070, 1320, 1570, 1820, 2070, 2320, 2570, 2820, 3070, 3320, 3570, 3820, 4070, 4320, 4570, 4820, 5070, 5320, 5570, 5820, 6070, 6320, 6570, 6820, 7070, 7320, 7570, 7820, 8070, 8320, 8570, 8820, 9070, 9320, 9570, 9820, 10070, 10320 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

The identity (1250*n^2 - 1800*n + 649)^2 - (25*n^2 - 36*n + 13)*(250*n - 180)^2 = 1 can be written as A154358(n)^2 - A154355(n)*a(n)^2 = 1. See also the third comment in A154357.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (2,-1).

FORMULA

G.f.: -10*(18 - 43*x)/(1-x)^2. - Bruno Berselli, Dec 13 2011

a(n) = 2*a(n-1) - a(n-2). - Vincenzo Librandi, Feb 21 2012

E.g.f.: 10*(-18 + 25*x)*exp(x). - G. C. Greubel, Sep 15 2016

MATHEMATICA

LinearRecurrence[{2, -1}, {-180, 70}, 50] (* Vincenzo Librandi, Feb 21 2012 *)

PROG

(PARI) for(n=0, 50, print1(250n - 180", ")); \\ Vincenzo Librandi, Feb 21 2012

(MAGMA) [250*n-180: n in [0..50]]; // Bruno Berselli, Sep 15 2016

CROSSREFS

Cf. A154361, A154359, A154358, A154357, A154355.

Sequence in context: A036203 A053325 A119542 * A253393 A260265 A117551

Adjacent sequences:  A154357 A154358 A154359 * A154361 A154362 A154363

KEYWORD

sign,easy

AUTHOR

Vincenzo Librandi, Jan 08 2009

EXTENSIONS

Offset changed and Librandi's comment rewritten by Bruno Berselli, Dec 13 2011

STATUS

approved

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Last modified May 14 18:54 EDT 2021. Contains 343900 sequences. (Running on oeis4.)