|
| |
|
|
A017817
|
|
a(0)=1, a(1)=a(2)=0, a(3)=1; a(n)=a(n-3)+a(n-4).
|
|
12
|
|
|
|
1, 0, 0, 1, 1, 0, 1, 2, 1, 1, 3, 3, 2, 4, 6, 5, 6, 10, 11, 11, 16, 21, 22, 27, 37, 43, 49, 64, 80, 92, 113, 144, 172, 205, 257, 316, 377, 462, 573, 693, 839, 1035, 1266, 1532, 1874, 2301, 2798, 3406, 4175, 5099, 6204, 7581, 9274, 11303, 13785, 16855, 20577, 25088
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,8
|
|
|
COMMENTS
|
Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=1, r=3, I={0,1}. [Vladimir Baltic, Mar 07 2012]
|
|
|
LINKS
|
Table of n, a(n) for n=0..57.
Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics 4 (2010), 119-135
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 484
E. Wilson, The Scales of Mt. Meru
Index entries for two-way infinite sequences
Index to sequences with linear recurrences with constant coefficients, signature (0,0,1,1).
|
|
|
FORMULA
|
G.f.: 1/(1-x^3-x^4).
a(n)/a(n-1) tends to A060007 . - Gary W. Adamson, Oct 22 2006
|
|
|
MATHEMATICA
|
a=b=c=0; d=1; lst={d}; Do[AppendTo[lst, e=a+b]; a=b; b=c; c=d; d=e, {n, 0, 5!}]; lst [From Vladimir Joseph Stephan Orlovsky, May 28 2010]
|
|
|
PROG
|
(PARI) a(n)=polcoeff(if(n<0, (1+x)/(1+x-x^4), 1/(1-x^3-x^4))+x*O(x^abs(n)), abs(n))
|
|
|
CROSSREFS
|
A003269(n)=a(-4-n)(-1)^n.
Sequence in context: A131336 A052253 A127838 * A189913 A053268 A101417
Adjacent sequences: A017814 A017815 A017816 * A017818 A017819 A017820
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
N. J. A. Sloane.
|
|
|
EXTENSIONS
|
More terms from Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Dec 17 1999
|
|
|
STATUS
|
approved
|
| |
|
|
