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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171442 Expansion of (1+x)^7/(1-x). 7
1, 8, 29, 64, 99, 120, 127, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n)=2^7=128 for n>=7. We observe that this sequence is the transform of A171441 by T such that: T(u_0,u_1,u_2,u_3,u_4,u_5,...)=(u_0,u_0+u_1,u_1+u_2,u_2+u_3,u_3+u_4,...).

REFERENCES

(Revue bimestrielle), Richard Choulet, Une nouvelle formule de combinatoire ?, Mathematique et Pedagogie, 157 (2006), 53-60.

LINKS

Table of n, a(n) for n=0..52.

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

FORMULA

With m=8, a(n)=sum(C(m,n-2*k),k=0..floor(n/2)).

EXAMPLE

a(5)=C(8,5-0)+C(8,5-2)+C(8,5-4)=56+56+8=120.

MAPLE

m:=8:for n from 0 to 40 do a(n):=sum('binomial(m, n-2*k)', k=0..floor(n/2)): od : seq(a(n), n=0..40);

MATHEMATICA

CoefficientList[Series[(1+x)^7/(1-x), {x, 0, 60}], x] (* Harvey P. Dale, Apr 30 2012 *)

CROSSREFS

Cf. A040000, A113311, A115291, A171418, A171440, A171441, A171443.

Sequence in context: A299802 A299678 A300310 * A247541 A093809 A244244

Adjacent sequences:  A171439 A171440 A171441 * A171443 A171444 A171445

KEYWORD

nonn,easy

AUTHOR

Richard Choulet, Dec 09 2009

EXTENSIONS

Definition rewritten by Bruno Berselli, Sep 23 2011

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 October 19 06:19 EDT 2018. Contains 316336 sequences. (Running on oeis4.)