

A079980


Number of permutations of length 2n satisfying k<=p(i)i<=r and p(i)i not in I, i=1..2n, with k=3, r=3, I={2,0,1,2}. There is no one such permutation of length 2n+1.


1



1, 0, 1, 2, 3, 8, 12, 27, 52, 95, 196, 369, 720, 1408, 2709, 5292, 10249, 19894, 38675, 74992, 145692, 282823, 549000, 1066095, 2069496, 4018065, 7801024, 15144960, 29404281, 57086680, 110832225, 215178138, 417759539, 811069560, 1574664364
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,4


LINKS

Table of n, a(n) for n=0..34.
Vladimir Baltic, On the number of certain types of strongly restricted permutations, Applicable Analysis and Discrete Mathematics Vol. 4, No 1 (2010), 119135
Index entries for linear recurrences with constant coefficients, signature (0,1,4,2,2,2,1,0,1).


FORMULA

Recurrence: a(n) = a(n2)+4*a(n3)+2*a(n4)+2*a(n5)2*a(n6)+a(n7)+a(n9).
G.f.: (x^62*x^3+1)/(x^9+x^72*x^6+2*x^5+2*x^4+4*x^3+x^21).


CROSSREFS

Subsequence of A079981.
Sequence in context: A242516 A282281 A321175 * A025080 A024468 A247355
Adjacent sequences: A079977 A079978 A079979 * A079981 A079982 A079983


KEYWORD

nonn,easy


AUTHOR

Vladimir Baltic, Feb 17 2003


STATUS

approved



