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%I #4 May 10 2013 12:44:47
%S 1,1,1,3,4,7,12,22,33,57,103,169,277,479,824,1368,2306,3941,6657,
%T 11206,18998,32194,54325,91880,155633,263120,444674,752545,1273278,
%U 2152704,3640801,6159723,10418147,17618849,29802480,50410743,85259765
%N Number of compositions of n such that two adjacent parts are not equal modulo 4.
%D I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 2.4.13).
%F G.f.: -(x^4-x-1)*(x^4-x^2-1)*(x^4-x^3-1)/(x^16-x^15-x^14-3*x^12+3*x^11+x^10+2*x^9+6*x^8-x^7-3*x^6-2*x^5-5*x^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)).
%Y Cf. A003242, A062200-A062203.
%K nonn
%O 0,4
%A _Vladeta Jovovic_, Jun 13 2001
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