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!)
A015508 a(1)=1, a(n) = sum_{k=1}^{k=n-1} (7^k-1)/6 a(k). 0
1, 1, 9, 522, 209322, 586520244, 11501075464596, 1578614616119517768, 1516734501782248791012168, 10200952598655696033329019125136, 480252779391204632593567857157274897424, 158269444415262012661462389451687149577571916192 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..12.

FORMULA

a(n) = ((7^(n-1) + 5)/6) * a(n-1). - Vincenzo Librandi, Nov 12 2012

PROG

(MAGMA) I:=[1, 1, 9]; [n le 3 select I[n] else ((7^(n-1) + 5)/6) * Self(n-1): n in [1..15]]; // Vincenzo Librandi, Nov 12 2012

CROSSREFS

Sequence in context: A230671 A281443 A003398 * A281800 A266889 A054608

Adjacent sequences:  A015505 A015506 A015507 * A015509 A015510 A015511

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

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 June 26 09:31 EDT 2022. Contains 354879 sequences. (Running on oeis4.)