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A123531
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Triangle read by rows: CP(n,i) for n>=0 and 3n+1 >= i >= 0, gives the absolute value of the coefficients of the chromatic polynomial of C_3 X P_n factored in the form x(x-1)^i.
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1
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1, 1, 1, 4, 8, 9, 4, 1, 7, 25, 57, 89, 56, 16, 1, 10, 51, 171, 411, 735, 986, 977, 684, 304, 64, 1, 13, 86, 378, 1219, 3027, 5930, 9254, 11485, 11185, 8304, 4448, 1536, 256
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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REFERENCES
| T. Pfaff & J. Walker, The Chromatic Polynomial of P_2 X P_n and C_3 x P_n. (to be submitted 2006)
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FORMULA
| CP(n,i) = CP(n-1, i) +3CP(n-1, i-1)+5CP(n-1, i-2)+4CP(n-1, i-3), with CP(0,0)=CP(0,1)=1; n>=0 and 3n+1 >= i >= 0
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EXAMPLE
| The chromatic polynomial of C_3 X P_2 is: x(x-1)^5-4x(x-1)^4+8x(x-1)^3-9x(x-1)^2+4x(x-1)^1 and so CP(1,0)=1, CP(1,1)=4, CP(1,2)=8, CP(1,3)=9 and CP(1,4)=4
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CROSSREFS
| Cf. A027907.
Sequence in context: A153109 A198736 A117180 * A201522 A117181 A194623
Adjacent sequences: A123528 A123529 A123530 * A123532 A123533 A123534
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KEYWORD
| nonn,tabl
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AUTHOR
| Thomas J. Pfaff (tpfaff(AT)ithaca.edu), Oct 02 2006
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