

A108693


Number of circular sequences of distinct positive integers between 1 and n such that the sum of any two consecutive elements is at least n+1.


0




OFFSET

1,2


LINKS

Table of n, a(n) for n=1..10.


EXAMPLE

For n=4 the circular sequences are 3, 4, 14, 23, 24, 34, 234 and 243, so a(4)=8.


CROSSREFS

Sequence in context: A145671 A316522 A317712 * A026096 A098864 A002546
Adjacent sequences: A108690 A108691 A108692 * A108694 A108695 A108696


KEYWORD

nonn


AUTHOR

Daniel Gulotta (dgulotta(AT)mit.edu), Jun 18 2005


STATUS

approved



