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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056520 (n+2)*(2*n^2-n+3)/6. 19
1, 2, 6, 15, 31, 56, 92, 141, 205, 286, 386, 507, 651, 820, 1016, 1241, 1497, 1786, 2110, 2471, 2871, 3312, 3796, 4325, 4901, 5526, 6202, 6931, 7715, 8556, 9456, 10417, 11441, 12530, 13686, 14911, 16207, 17576, 19020, 20541, 22141, 23822 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) = A000330(n)+1.

Hankel transform of A030238. - Paul Barry, Oct 16 2007

Equals (1, 2, 3, 4, 5,...) convolved with (1, 0, 3, 5, 7, 9,...). - Gary W. Adamson, Jul 31 2010

a(n) equals n!^2 times the determinant of the n X n matrix whose (i,j)-entry is 1 + KroneckerDelta[i, j] (-1 + (1 + i^2)/i^2). - John M. Campbell, May 20 2011

Let b(0)=b(1)=1, b(n)=max(b(n-1)+(n-1)^2,b(n-2)+(n-2)^2); then A056520(n)=b(n+1). - Yalcin Aktar, Jul 28 2011

Positions of ones in A253903. - Harvey P. Dale, Mar 05 2015

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Guo-Niu Han, Enumeration of Standard Puzzles\Guo-Niu Han, Enumeration of Standard Puzzles [Cached copy]

Amit Kumar Singh, Akash Kumar and Thambipillai Srikanthan, Accelerating Throughput-aware Run-time Mapping for Heterogeneous MPSoCs, ACM Transactions on Design Automation of Electronic Systems, 2012. - From N. J. A. Sloane, Dec 25 2012

FORMULA

a(n) = a(n-1)+n^2.

G.f.: (1-2*x+4*x^2-x^3)/(1-x)^4. - Paul Barry, Apr 14 2010

MATHEMATICA

a[n_] := (n+2)*(2*n^2-n+3)/6; Table[a[n], {n, 0, 100}] (* Vladimir Joseph Stephan Orlovsky, Dec 17 2008 *)

s = 1; lst = {s}; Do[s += n^2; AppendTo[lst, s], {n, 1, 41, 1}]; lst (* Zerinvary Lajos, Jul 12 2009 *)

Table[n!^2*Det[Array[KroneckerDelta[#1, #2](((#1^2+1)/(#1^2))-1)+1&, {n, n}]], {n, 1, 20}] (* John M. Campbell, May 20 2011 *)

FoldList[#1 + #2^2 &, 1, Range@ 40] (* Robert G. Wilson v, Oct 28 2011 *)

PROG

(MAGMA)[(n+2)*(2*n^2-n+3)/6: n in [0..40]]; // Vincenzo Librandi, May 24 2011

(PARI) a(n)=(n+2)*(2*n^2-n+3)/6 \\ Charles R Greathouse IV, Jul 02 2013

CROSSREFS

Cf. A253903.

Sequence in context: A236111 A230455 A141126 * A289961 A290068 A289935

Adjacent sequences:  A056517 A056518 A056519 * A056521 A056522 A056523

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Laura Kasavan (maui12129(AT)cswebmail.com), Aug 26 2000

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 22 09:35 EST 2017. Contains 295076 sequences.