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!)
A213392 Number of (w,x,y) with all terms in {0,...,n} and 2*max(w,x,y) >= 3*min(w,x,y). 2
1, 7, 25, 61, 115, 199, 319, 469, 667, 919, 1213, 1573, 2005, 2491, 3061, 3721, 4447, 5275, 6211, 7225, 8359, 9619, 10969, 12457, 14089, 15823, 17713, 19765, 21931, 24271, 26791, 29437, 32275, 35311, 38485, 41869, 45469, 49219, 53197 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n)+A213391(n) = (n+1)^3.

For a guide to related sequences, see A212959.

LINKS

Table of n, a(n) for n=0..38.

Index entries for linear recurrences with constant coefficients, signature (2,-1,2,-4,2,-1,2,-1).

FORMULA

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

G.f.: -(-1-5*x-x^6-12*x^2-16*x^3-8*x^4-6*x^5+x^7) / ((x^2+x+1)^2*(x-1)^4).

MATHEMATICA

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

(Do[If[2*Max[w, x, y] >= 3*Min[w, x, y], s = s + 1],

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

m = Map[t[#] &, Range[0, 45]]   (* A213391 *)

CROSSREFS

Cf. A212959.

Sequence in context: A162264 A034135 A212136 * A061600 A098538 A033814

Adjacent sequences:  A213389 A213390 A213391 * A213393 A213394 A213395

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jun 11 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 January 28 13:05 EST 2020. Contains 331321 sequences. (Running on oeis4.)