login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A098610 a(n) = 10^n + (-1)^n. 3
2, 9, 101, 999, 10001, 99999, 1000001, 9999999, 100000001, 999999999, 10000000001, 99999999999, 1000000000001, 9999999999999, 100000000000001, 999999999999999, 10000000000000001, 99999999999999999, 1000000000000000001, 9999999999999999999, 100000000000000000001 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

FORMULA

a(n) = A098611(n)+2*(-1)^n.

a(n) = A098609(n)/A098611(n).

a(n) = A098609(n)/(11*A015585(n)).

a(n) = 9*A094028(n+1)/A015585(n).

From Chai Wah Wu, Sep 22 2016: (Start)

a(n) = 9*a(n-1) + 10*a(n-2) for n > 1.

G.f.: (9*x - 2)/((x + 1)*(10*x - 1)). (End)

MATHEMATICA

Total/@Partition[Riffle[10^Range[0, 20], {1, -1}], 2] (* or *) Table[10^n+(-1)^n, {n, 0, 20}] (* Harvey P. Dale, Aug 20 2012 *)

PROG

(MAGMA) [10^n+(-1)^n: n in [0..20]]; // Vincenzo Librandi, Sep 23 2016

CROSSREFS

Sequence in context: A277180 A013520 A041239 * A226391 A125815 A132494

Adjacent sequences:  A098607 A098608 A098609 * A098611 A098612 A098613

KEYWORD

easy,nonn

AUTHOR

Henry Bottomley, Sep 17 2004

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 July 2 08:02 EDT 2020. Contains 335398 sequences. (Running on oeis4.)