A137517 a(0) = 121; for n>0, a(n) = a(n-1) - n + 1.

121, 121, 120, 118, 115, 111, 106, 100, 93, 85, 76, 66, 55, 43, 30, 16, 1, -15, -32, -50, -69, -89, -110, -132, -155, -179, -204, -230, -257, -285, -314, -344, -375, -407, -440, -474, -509, -545, -582, -620, -659, -699, -740, -782, -825, -869, -914, -960

Offset

0,1

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

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

Formula

a(n) = (1/2)*(242 - n^2 + n) - Alexander R. Povolotsky, Apr 26 2008

a(0)=121, a(1)=121, a(2)=120, a(n)=3*a(n-1)-3*a(n-2)+a(n-3). - Harvey P. Dale, Dec 07 2012

G.f.: -(12*x-11)*(10*x-11) / (x-1)^3 . - R. J. Mathar, Nov 07 2015

Mathematica

RecurrenceTable[{a[0]==121, a[n]==a[n-1]-n+1}, a, {n, 60}] (* or *) LinearRecurrence[{3, -3, 1}, {121, 121, 120}, 60] (* Harvey P. Dale, Dec 07 2012 *)
CoefficientList[Series[-(12*x - 11)*(10*x - 11)/(x - 1)^3, {x, 0, 50}], x] (* G. C. Greubel, Feb 23 2017 *)

Prog

(PARI) my(x='x + O('x^50)); Vec(-(12*x - 11)*(10*x - 11)/(x - 1)^3) \\ G. C. Greubel, Feb 23 2017

Crossrefs

Sequence in context: A202003 A109838 A014734 * A364804 A014735 A137850

Adjacent sequences: A137514 A137515 A137516 * A137518 A137519 A137520

Keyword

sign,easy

Author

Frederic Sebastian (frederic.sebastian(AT)gmail.com), Apr 24 2008

Status

approved