|
Search: id:A143450
|
|
|
| A143450 |
|
Expansion of 1/(x^k*(1-x-2*x^(k+1))) for k=7. |
|
+0
2
|
|
| 1, 3, 5, 7, 9, 11, 13, 15, 17, 23, 33, 47, 65, 87, 113, 143, 177, 223, 289, 383, 513, 687, 913, 1199, 1553, 1999, 2577, 3343, 4369, 5743, 7569, 9967, 13073, 17071, 22225, 28911, 37649, 49135, 64273, 84207, 110353, 144495, 188945, 246767, 322065
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
COMMENT
|
a(n) is also the number of length n ternary words with at least 7 0-digits between any other digits.
|
|
FORMULA
|
G.f.: 1/(x^7*(1-x-2*x^8)).
|
|
MAPLE
|
a := proc(k::nonnegint) local n, i, j; if k=0 then unapply (3^n, n) else unapply ((Matrix(k+1, (i, j)-> if (i=j-1) or j=1 and i=1 then 1 elif j=1 and i=k+1 then 2 else 0 fi)^(n+k))[1, 1], n) fi end(7): seq (a(n), n=0..61);
|
|
CROSSREFS
|
7th column of A143453.
Sequence in context: A066640 A137507 A061808 this_sequence A005842 A081110 A143449
Adjacent sequences: A143447 A143448 A143449 this_sequence A143451 A143452 A143453
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Alois P. Heinz (heinz(AT)hs-heilbronn.de), Aug 16 2008
|
|
|
Search completed in 0.002 seconds
|
