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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A170746 Expansion of g.f.: (1+x)/(1-26*x). 50
1, 27, 702, 18252, 474552, 12338352, 320797152, 8340725952, 216858874752, 5638330743552, 146596599332352, 3811511582641152, 99099301148669952, 2576581829865418752, 66991127576500887552, 1741769316989023076352, 45286002241714599985152, 1177436058284579599613952 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Kenny Lau, Table of n, a(n) for n = 0..706

Index entries for linear recurrences with constant coefficients, signature (26).

FORMULA

a(n) = Sum_{k=0..n} A097805(n,k)*(-1)^(n-k)*27^k. - Philippe Deléham, Dec 04 2009

a(0) = 1; for n>0, a(n) = 27*26^(n-1). - Vincenzo Librandi, Dec 05 2009

E.g.f.: (27*exp(26*x) - 1)/26. - G. C. Greubel, Sep 25 2019

MAPLE

k:=27; seq(`if`(n=0, 1, k*(k-1)^(n-1)), n = 0..25); # G. C. Greubel, Sep 25 2019

MATHEMATICA

CoefficientList[Series[(1+x)/(1-26x), {x, 0, 20}], x] (* or *) Join[ {1}, NestList[26#&, 27, 20]] (* Harvey P. Dale, Jun 16 2016 *)

PROG

(Python) for i in range(31):print(i, 27*26**(i-1) if i>0 else 1) # Kenny Lau, Aug 03 2017

(PARI) vector(26, n, k=27; if(n==1, 1, k*(k-1)^(n-2))) \\ G. C. Greubel, Sep 25 2019

(MAGMA) k:=27; [1] cat [k*(k-1)^(n-1): n in [1..25]]; // G. C. Greubel, Sep 25 2019

(Sage) k=27; [1]+[k*(k-1)^(n-1) for n in (1..25)] # G. C. Greubel, Sep 25 2019

(GAP) k:=27;; Concatenation([1], List([1..25], n-> k*(k-1)^(n-1) )); # G. C. Greubel, Sep 25 2019

CROSSREFS

Cf. A003945, A097805.

Sequence in context: A170612 A170660 A170708 * A218729 A171332 A097781

Adjacent sequences:  A170743 A170744 A170745 * A170747 A170748 A170749

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 04 2009

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 17 21:57 EDT 2019. Contains 328134 sequences. (Running on oeis4.)