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A062201
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Number of compositions of n such that two adjacent parts are not equal modulo 3.
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1
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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REFERENCES
| I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 2.4.13).
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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)).
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CROSSREFS
| Cf. A003242, A062200-A062203.
Sequence in context: A049929 A060738 A090651 * A049895 A051530 A048040
Adjacent sequences: A062198 A062199 A062200 * A062202 A062203 A062204
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 13 2001
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