|
| |
|
|
A077936
|
|
Expansion of 1/(1-2*x-2*x^2-x^3).
|
|
3
| |
|
|
1, 2, 6, 17, 48, 136, 385, 1090, 3086, 8737, 24736, 70032, 198273, 561346, 1589270, 4499505, 12738896, 36066072, 102109441, 289089922, 818464798, 2317218881, 6560457280, 18573817120, 52585767681, 148879626882, 421504606246, 1193354233937, 3378597307248
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,2
|
|
|
COMMENTS
| Row sum of A158687. [From Paul Barry (pbarry(AT)wit.ie), Mar 24 2009]
|
|
|
LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 0..500
Index to sequences with linear recurrences with constant coefficients, signature (2,2,1).
|
|
|
FORMULA
| a(n)=sum{k=0..n, sum{j=0..n-k, C(n-j,k)*C(2k,j)}}. [From Paul Barry (pbarry(AT)wit.ie), Mar 24 2009]
|
|
|
MATHEMATICA
| CoefficientList[Series[1/(1-2*x-2*x^2-x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{2, 2, 1}, {1, 2, 6}, 40] (* From Vladimir Joseph Stephan Orlovsky, Jan 30 2012 *)
|
|
|
PROG
| (PARI) Vec(1/(1-2*x-2*x^2-x^3)+O(x^99)) \\ Charles R Greathouse IV, Jan 31 2012
|
|
|
CROSSREFS
| Sequence in context: A018915 A019487 * A077983 A036365 A052536 A122100
Adjacent sequences: A077933 A077934 A077935 * A077937 A077938 A077939
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 17 2002
|
| |
|
|
