login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A213486 Number of (w,x,y) with all terms in {0,...,n} and |w-x|+|x-y|+|y-w| > w+x+y. 3
0, 3, 12, 27, 48, 78, 120, 174, 240, 321, 420, 537, 672, 828, 1008, 1212, 1440, 1695, 1980, 2295, 2640, 3018, 3432, 3882, 4368, 4893, 5460, 6069, 6720, 7416, 8160, 8952, 9792, 10683, 11628, 12627, 13680, 14790, 15960, 17190, 18480, 19833 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Every term is divisible by 3.

a(n)+A213487(n)=(n+1)^3.

For a guide to related sequences, see A212959.

LINKS

Table of n, a(n) for n=0..41.

Index entries for linear recurrences with constant coefficients, signature (4,-7,8,-7,4,-1).

FORMULA

a(n) = 4*a(n-1)-7*a(n-2)+8*a(n-3)-7*a(n-4)+4*a(n-5)-a(n-6).

G.f.: 3*x/((1 - x)^4 (1 + x^2)).

MATHEMATICA

t = Compile[{{n, _Integer}}, Module[{s = 0},

(Do[If[w + x + y < Abs[w - x] + Abs[x - y] + Abs[y - w],

s = s + 1], {w, 0, n}, {x, 0, n}, {y, 0, n}]; s)]];

m = Map[t[#] &, Range[0, 60]]   (* A213486 *)

CROSSREFS

Cf. A212959.

Sequence in context: A061936 A074630 A033428 * A018230 A058034 A294416

Adjacent sequences:  A213483 A213484 A213485 * A213487 A213488 A213489

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jun 13 2012

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 July 26 17:37 EDT 2021. Contains 346294 sequences. (Running on oeis4.)