A106355 Number of compositions of n into 6 parts such that no two adjacent parts are equal.

2, 10, 30, 76, 168, 320, 580, 968, 1558, 2380, 3540, 5078, 7160, 9804, 13238, 17510, 22884, 29418, 37462, 47054, 58638, 72272, 88454, 107262, 129312, 154644, 183994, 217442, 255782, 299114, 348386, 403652, 466012, 535550, 613442, 699812, 796012

Offset: 9

Author

Christian G. Bower, Apr 29 2005

Keywords

• nonn
• easy

Links

• Alois P. Heinz, Table of n, a(n) for n = 9..1000
• A. Knopfmacher and H. Prodinger, On Carlitz compositions, European Journal of Combinatorics, Vol. 19, 1998, pp. 579-589.

Crossrefs

Column 6 of A106351. Cf. A003242.

Formula

G.f.: 2 *(16*x^12 +16*x^11 +31*x^10 +40*x^9 +53*x^8 +51*x^7 +51*x^6 +39*x^5 +31*x^4 +18*x^3 +9*x^2 +4*x+1) *x^9 / ((x^2-x+1) *(x^4+x^3+x^2+x+1) *(x^2+1) *(x^2+x+1)^2 *(x+1)^3 *(x-1)^6). - Alois P. Heinz, Sep 04 2015

Extensions

Replaced broken link, Vaclav Kotesovec, May 01 2014