A174084 Number of permutations of length n with no consecutive triples i,...i+r,...i+2r for all r, and for all equal spacings d.

21, 94, 544, 3509, 26799, 223123

Offset

4,1

Comments

Here we count both the sequence 1,2,3 (r=1) as a progression in 1,2,3,0,4,5, (note d=1) and in 1,0,2,4,3,5 (here, d=2).

Links

Table of n, a(n) for n=4..9.

Example

For n=4 there are 4!-a(4)=3 with some progression. These are (0,1,2,3), (1,2,3,0), and (3,0,1,2). Here for all the progressions, r=1 and d=1, hence this term is the same as a(4) in A002628.

Crossrefs

Cf. A002628, A174080, A174085, A174086, A174087.

Sequence in context: A219423 A123213 A296822 * A193218 A220157 A264239

Adjacent sequences: A174081 A174082 A174083 * A174085 A174086 A174087

Keyword

nonn

Author

Isaac Lambert, Apr 20 2010

Status

approved