A262197 Number of compositions of n such that the maximal distance between two identical parts equals four.

0, 1, 3, 9, 21, 46, 92, 180, 330, 595, 1039, 1793, 3023, 5030, 8248, 13388, 21518, 34231, 54079, 84607, 131603, 203050, 311738, 474974, 720666, 1086125, 1629815, 2431647, 3612665, 5339710, 7860366, 11519856, 16816312, 24448029, 35409609

Offset

4,3

Links

Table of n, a(n) for n=4..38.

Example

a(5) = 1: 11111.
a(6) = 3: 11121, 11211, 12111.
a(7) = 9: 11131, 11221, 11311, 12121, 12211, 13111, 21112, 111112, 211111.
a(8) = 21: 11141, 11231, 11321, 11411, 12131, 12221, 12311, 13121, 13211, 14111, 21122, 21212, 22112, 111113, 111212, 112112, 121112, 211121, 211211, 212111, 311111.

Crossrefs

Column k=4 of A262191.

Sequence in context: A063830 A062444 A141156 * A014286 A000714 A267226

Adjacent sequences: A262194 A262195 A262196 * A262198 A262199 A262200

Keyword

nonn

Author

Alois P. Heinz, Sep 14 2015

Status

approved