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.

1, 2, 4, 8, 15, 36, 80, 244, 677, 2530

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 * A371351 A026096 A098864

Adjacent sequences: A108690 A108691 A108692 * A108694 A108695 A108696

Keyword

nonn

Author

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

Status

approved