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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A125200 n*(4*n^2 + n -1)/2. 3
2, 17, 57, 134, 260, 447, 707, 1052, 1494, 2045, 2717, 3522, 4472, 5579, 6855, 8312, 9962, 11817, 13889, 16190, 18732, 21527, 24587, 27924, 31550, 35477, 39717, 44282, 49184, 54435, 60047, 66032, 72402, 79169, 86345, 93942, 101972, 110447, 119379 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = Sum(4*n*k - n - k: 1<=k<=n), sums of rows of the triangle in A125199.

A003415(A003415(a(n))) = 2*A016969(n-1).

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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

FORMULA

a(n)= 4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4). [R. J. Mathar, Feb 12 2010]

G.f.: x*(2+9*x+x^2)/(x-1)^4. [R. J. Mathar, Feb 12 2010]

a(n) = sum( A033568(i), i=1..n ). [Bruno Berselli, Jul 22 2013]

MATHEMATICA

LinearRecurrence[{4, -6, 4, -1}, {2, 17, 57, 134}, 40] (* Harvey P. Dale, Feb 05 2013 *)

PROG

(MAGMA) [n*(4*n^2 +n-1)div 2:n in [1..40]]; // Vincenzo Librandi, Dec 27 2010

CROSSREFS

Sequence in context: A212836 A125609 A100518 * A175450 A071402 A228641

Adjacent sequences:  A125197 A125198 A125199 * A125201 A125202 A125203

KEYWORD

nonn,easy

AUTHOR

Reinhard Zumkeller, Nov 24 2006

EXTENSIONS

Definition corrected by Vincenzo Librandi, Dec 27 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 15 18:51 EST 2018. Contains 317240 sequences. (Running on oeis4.)