login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A261799 Number of 7-compositions of n: matrices with 7 rows of nonnegative integers with positive column sums and total element sum n. 2
1, 7, 77, 819, 8687, 92141, 977347, 10366833, 109962202, 1166381804, 12371946734, 131230670312, 1391978902090, 14764881252772, 156612803600094, 1661210126351328, 17620647995924820, 186904251828901124, 1982515022137687464, 21028766197355391048 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Also the number of compositions of n where each part i is marked with a word of length i over a septenary alphabet whose letters appear in alphabetical order.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..975

Index entries for linear recurrences with constant coefficients, signature (14,-42,70,-70,42,-14,2).

FORMULA

G.f.: (1-x)^7/(2*(1-x)^7-1).

a(n) = A261780(n,7).

MAPLE

a:= proc(n) option remember; `if`(n=0, 1,

      add(a(n-j)*binomial(j+6, 6), j=1..n))

    end:

seq(a(n), n=0..20);

CROSSREFS

Column k=7 of A261780.

Sequence in context: A061546 A002281 A097983 * A246236 A267709 A234466

Adjacent sequences:  A261796 A261797 A261798 * A261800 A261801 A261802

KEYWORD

nonn,easy

AUTHOR

Alois P. Heinz, Sep 01 2015

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 29 06:39 EDT 2017. Contains 288859 sequences.