A062201 Number of compositions of n such that two adjacent parts are not equal modulo 3.

1, 1, 1, 3, 4, 5, 13, 17, 23, 54, 75, 106, 224, 329, 482, 942, 1436, 2163, 4004, 6255, 9619, 17144, 27220, 42513, 73785, 118402, 187082, 318715, 514958, 820744, 1380185, 2239747, 3592811, 5987313, 9742606, 15703097, 26004453, 42385083

Offset

0,4

References

I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 2.4.13).

Links

Table of n, a(n) for n=0..37.

Formula

G.f.: -(x^3-x-1)*(x^3-x^2-1)/(x^9-x^8-x^7-2*x^6+x^5+x^4+4*x^3-1). Generally, g.f. for the number of compositions of n such that two adjacent parts are not equal modulo p is 1/(1-Sum_{i=1..p} x^i/(1+x^i-x^p)).

Crossrefs

Cf. A003242, A062200-A062203.

Sequence in context: A060738 A090651 A242497 * A352908 A211518 A049895

Adjacent sequences: A062198 A062199 A062200 * A062202 A062203 A062204

Keyword

nonn

Author

Vladeta Jovovic, Jun 13 2001

Status

approved