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Search: id:A123531
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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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+0
2
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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; listen)
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OFFSET
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0,4
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REFERENCES
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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
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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
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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
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Cf. A027907.
Sequence in context: A096412 A153109 A117180 this_sequence A117181 A108616 A154177
Adjacent sequences: A123528 A123529 A123530 this_sequence A123532 A123533 A123534
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KEYWORD
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nonn,tabl
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AUTHOR
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Thomas J. Pfaff (tpfaff(AT)ithaca.edu), Oct 02 2006
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