login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A156676 a(n) = 81*n^2 - 44*n + 6. 5
6, 43, 242, 603, 1126, 1811, 2658, 3667, 4838, 6171, 7666, 9323, 11142, 13123, 15266, 17571, 20038, 22667, 25458, 28411, 31526, 34803, 38242, 41843, 45606, 49531, 53618, 57867, 62278, 66851, 71586, 76483, 81542, 86763, 92146, 97691, 103398 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

The identity (6561*n^2-3564*n+485)^2-(81*n^2-44*n+6)*(729*n-198)^2=1 can be written as A156774(n)^2-a(n)* A156772(n)^2=1 for n>0.

a(n) = A000290(A017245(n-1)) - A017137(n-1). [Reinhard Zumkeller, Jul 13 2010]

LINKS

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

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

FORMULA

a(n) = 3*a(n-1) -3*a(n-2) +a(n-3).

G.f.: (6+25*x+131*x^2)/(1-x)^3.

MAPLE

A156676:=n->81*n^2-44*n+6: seq(A156676(n), n=0..100); # Wesley Ivan Hurt, Apr 26 2017

MATHEMATICA

LinearRecurrence[{3, -3, 1}, {6, 43, 242}, 40]

PROG

(MAGMA) [81*n^2 - 44*n + 6: n in [0..40] ]

(PARI) a(n)=81*n^2-44*n+6 \\ Charles R Greathouse IV, Dec 23 2011

CROSSREFS

Cf. A156772, A156774.

Sequence in context: A299375 A097298 A012872 * A256713 A099322 A014989

Adjacent sequences:  A156673 A156674 A156675 * A156677 A156678 A156679

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Feb 15 2009

EXTENSIONS

Edited by Charles R Greathouse IV, Jul 25 2010

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 21 10:49 EST 2019. Contains 320372 sequences. (Running on oeis4.)