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

 

Logo

The OEIS is looking to hire part-time people to help edit core sequences, upload scanned documents, process citations, fix broken links, etc. - Neil Sloane, njasloane@gmail.com

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A161702 (-n^3 + 9n^2 - 5n + 3)/3. 17
1, 2, 7, 14, 21, 26, 27, 22, 9, -14, -49, -98, -163, -246, -349, -474, -623, -798, -1001, -1234, -1499, -1798, -2133, -2506, -2919, -3374, -3873, -4418, -5011, -5654, -6349, -7098, -7903, -8766, -9689, -10674, -11723, -12838, -14021, -15274 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

{a(k): 0 <= k < 4} = divisors of 14:

a(n) = A027750(A006218(13) + k + 1), 0 <= k < A000005(14).

LINKS

Table of n, a(n) for n=0..39.

R. Zumkeller, Enumerations of Divisors

Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

FORMULA

a(n) = C(n,0) + C(n,1) + 4*C(n,2) - 2*C(n,3).

G.f.: (1-2*x+5*x^2-6*x^3)/(1-x)^4. [Colin Barker, Jan 08 2012]

a(0)=1, a(1)=2, a(2)=7, a(3)=14, a(n)=4*a(n-1)-6*a(n-2)+4*a(n-3)-a(n-4). - Harvey P. Dale, Jun 15 2013

EXAMPLE

Differences of divisors of 14 to compute the coefficients of their interpolating polynomial, see formula:

1 ... 2 ... 7 ... 14

.. 1 ... 5 ... 7

..... 4 ... 2

....... -2.

MATHEMATICA

Table[(-n^3+9n^2-5n+3)/3, {n, 0, 40}] (* or *) LinearRecurrence[{4, -6, 4, -1}, {1, 2, 7, 14}, 40] (* Harvey P. Dale, Jun 15 2013 *)

PROG

(MAGMA)[(-n^3 + 9*n^2 - 5*n + 3)/3: n in [0..50]]; [From Vincenzo Librandi, Dec 27 2010]

(PARI) a(n)=(-n^3+9*n^2-5*n+3)/3 \\ Charles R Greathouse IV, Sep 24 2015

CROSSREFS

Cf. A005408, A000124, A016813, A086514, A000125, A058331, A002522, A161701, A161703, A000127, A161704, A161706-A161708, A161710, A080856, A161711-A161713, A161715, A006261.

Sequence in context: A018363 A187142 A263398 * A114346 A087324 A261246

Adjacent sequences:  A161699 A161700 A161701 * A161703 A161704 A161705

KEYWORD

sign,easy

AUTHOR

Reinhard Zumkeller, Jun 17 2009

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 30 06:51 EDT 2017. Contains 287302 sequences.