login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A213288 Number of 9-length words w over n-ary alphabet such that for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z. 2
0, 1, 162, 2074, 13280, 64924, 273248, 1050777, 3754472, 12602451, 39598078, 115470300, 311272072, 777274550, 1808153452, 3946185587, 8137258032, 15957939797, 29935676058, 53988338158, 94013898576, 158665898944, 260355640952, 416527654621, 651260985944 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
Index entries for linear recurrences with constant coefficients, signature (10,-45,120,-210,252,-210,120,-45,10,-1).
FORMULA
a(n) = n*(3353416 -9177198*n +10002755*n^2 -5796570*n^3 +1984509*n^4 -416052*n^5 +52920*n^6 -3780*n^7 +120*n^8)/120.
G.f.: x*(1+152*x +499*x^2 -290*x^3 +6224*x^4 +6496*x^5 +41203*x^6 +52034*x^7 +256561*x^8) / (1-x)^10.
EXAMPLE
a(0) = 0: no word of length 9 is possible for an empty alphabet.
a(1) = 1: aaaaaaaaa for alphabet {a}.
a(2) = 162: aaaaaaaaa, aaaaaaaab, ..., baabababa, bbbbbbbbb for alphabet {a,b}.
MAPLE
a:= n-> n*(3353416+ (-9177198+ (10002755+ (-5796570+ (1984509+ (-416052+ (52920+ (-3780+120*n) *n) *n) *n) *n) *n) *n) *n)/120:
seq(a(n), n=0..40);
CROSSREFS
Row n=9 of A213276.
Sequence in context: A206145 A342850 A304166 * A302532 A288489 A303413
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Jun 08 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 10:22 EDT 2024. Contains 371268 sequences. (Running on oeis4.)