|
|
A211436
|
|
Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and 2w+3x+4y=0.
|
|
2
|
|
|
1, 1, 7, 11, 21, 27, 43, 51, 73, 83, 109, 123, 155, 169, 207, 225, 267, 287, 335, 357, 411, 435, 493, 521, 585, 613, 683, 715, 789, 823, 903, 939, 1025, 1063, 1153, 1195, 1291, 1333, 1435, 1481, 1587, 1635, 1747, 1797, 1915, 1967, 2089, 2145
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
For a guide to related sequences, see A211422.
|
|
LINKS
|
|
|
FORMULA
|
Empirical g.f.: (1 + x + 6*x^2 + 9*x^3 + 12*x^4 + 9*x^5 + 6*x^6 + x^7 + x^8) / ((1 - x)^3*(1 + x)^2*(1 + x^2)*(1 + x + x^2)). - Colin Barker, May 15 2017
|
|
MATHEMATICA
|
t[n_] := t[n] = Flatten[Table[2 w + 3 x + 4 y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
c[n_] := Count[t[n], 0]
t = Table[c[n], {n, 0, 80}] (* A211436 *)
(t - 1)/2 (* integers *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|