This site is supported by donations to The OEIS Foundation.
| Search: a007455 |
| Displaying 1-1 of 1 results found. | page 1 |
| Sort: relevance | references | number | modified | created | Format: long | short | data |
| A007455 | Number of subsequences of [ 1,...,n ] in which each odd number has an even neighbor.
(Formerly M2480) |
4 |
|---|---|---|
| 1, 1, 3, 5, 11, 17, 39, 61, 139, 217, 495, 773, 1763, 2753, 6279, 9805, 22363, 34921, 79647, 124373, 283667, 442961, 1010295, 1577629, 3598219, 5618809, 12815247, 20011685, 45642179, 71272673, 162557031, 253841389, 578955451, 904069513 (list; graph; refs; listen; history; edit; text; internal format) | OFFSET | 0,3 |
|---|---|
| COMMENTS | G.f. = (-1-x-2 x^3)/(-1+3 x^2+2 x^4) (* Harvey P. Dale, Feb 18 2011 *) |
| REFERENCES | N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). |
| LINKS | T. D. Noe, Table of n, a(n) for n=0..400 R. K. Guy, William O. J. Moser, Numbers of subsequences without isolated odd members, Fibonacci Quarterly, 34, No. 2, 152-155 (1996). Index entries for linear recurrences with constant coefficients, signature (0,3,0,2). |
| FORMULA |
a(n) = 3*a(n-2) + 2*a(n-4). |
| MATHEMATICA |
CoefficientList[Series[(-1-x-2 x^3)/(-1+3 x^2+2 x^4), {x, 0, 40}], x] (* Harvey P. Dale, Feb 18 2011 *) LinearRecurrence[{0, 3, 0, 2}, {1, 1, 3, 5}, 40] (* Harvey P. Dale, Feb 10 2015 *) |
| PROG |
(Haskell) a007455 n = a007455_list !! n a007455_list = 1 : 1 : 3 : 5 : zipWith (+) (map (* 2) a007455_list) (map (* 3) $ drop 2 a007455_list) -- Reinhard Zumkeller, Jul 16 2012 Auto-generate: |
| CROSSREFS | Cf. A007481, A007482, A007484. Sequence in context: A320353 A155989 A125557 * A034729 A115786 A252089 Adjacent sequences: A007452 A007453 A007454 * A007456 A007457 A007458 |
| KEYWORD | nonn,easy,nice |
| AUTHOR | |
| STATUS | approved |
| page 1 |
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 June 16 21:20 EDT 2019. Contains 324155 sequences. (Running on oeis4.)