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A136600 Triangle of coefficients of characteristic polynomials of a special type of Cartan matrix: E_n for E_6,E_7,E_8,E_11 example M(6)/ E_6: {{2, -1, 0, 0, 0, 0}, {-1, 2, -1, 0, 0, 0}, {0, -1, 2, -1, 0, -1}, {0, 0, -1, 2, -1, 0}, {0, 0, 0, -1, 2, 0}, {0, 0, -1, 0, 0, 2}},. +0
1
1, 2, -1, 4, -4, 1, 6, -11, 6, -1, 5, -20, 21, -8, 1, 4, -34, 56, -36, 10, -1, 3, -52, 125, -120, 55, -12, 1, 2, -73, 246, -329, 220, -78, 14, -1, 1, -96, 440, -784, 714, -364, 105, -16, 1, 0, -120, 730, -1679, 1992, -1364, 560, -136, 18, -1, -1, -144, 1140, -3304, 4949, -4356, 2379, -816, 171, -20, 1, -2, -167, 1694 (list; table; graph; listen)
OFFSET

1,2

COMMENT

Row sums are:

{1, 1, 1, 0, -1, -1, 0, 1, 1, 0, -1, -1, 0}

Solution for a polynomial recursion gives for higher polynomials:

p1 = Join[{1}, Table[CharacteristicPolynomial[MO[n], x], {n, 1, 12}]];

Table[Solve[{p1[[n]] - (a0*x - b0)*p1[[n - 1]] - c0*p1[[n - 2]] == 0, p1[[n + 1]] - (a0*x - b0)* p1[[n]] - c0*p1[[n - 1]] == 0, p1[[n + 2]] - (a0*x - b0)*p1[[n + 1]] - c0*p1[[n]] == 0}, {a0, b0, c0}], {n, 3, 10}];

Polynomial recursion:

P[x, n] = (2 - x)*P[x, n - 1] + P[x, n - 2]

REFERENCES

R. N. Cahn, Semi-Simple Lie Algebras and Their Representations, Dover, NY, 2006, ISBN 0-486-44999-8.page 139

E. B. Dynkin, Semisimple subalgebras of semisimple Lie algebras, Amer. Math. Soc. Transl, 1957

Sigurdur Helgasson, Differential Geometry, Lie Groups and Symmetric Spaces, Graduaste Studies in Mathematics, volume 34. A. M. S. :ISBN 0-8218-2848-7, 1978

FORMULA

h(n,m)=If[ n == m, a[n], If[n == m - 1 ||n == m + 1 || n == m - 3 || n == m + 3, If[n == m - 1 && m < d,b[m - 1], If[n == m + 1 && n < d, b[n - 1], If[n ==m - 3 || n == m + 3, If[n == m - 3 && m == d, c[m - 3], If[n == m + 3 && n == d, c[n - 3], 0]]]]]]] ; for n,m<=d

EXAMPLE

{1},

{2, -1},

{4, -4, 1},

{6, -11, 6, -1},

{5, -20, 21, -8, 1},

{4, -34, 56, -36, 10, -1},

{3, -52, 125, -120,55, -12, 1},

{2, -73, 246, -329, 220, -78, 14, -1},

{1, -96, 440, -784, 714, -364, 105, -16, 1},

{0, -120, 730, -1679, 1992, -1364, 560, -136, 18, -1},

{-1, -144, 1140, -3304, 4949, -4356, 2379,-816, 171, -20, 1},

{-2, -167, 1694, -6069, 11210, -12297, 8554, -3875, 1140, -210, 22, -1},

{-3, -188, 2415, -10528, 23540, -31448, 27026, -15488, 5984, -1540, 253, -24, 1}

MATHEMATICA

a[n_] := 2; b[n_] := -1; c[n_] := -1; T[n_, m_, d_] := If[ n == m, a[n], If[n == m - 1 || n == m + 1 || n ==m - 3 || n == m + 3, If[n == m - 1 &&m < d, b[m - 1], If[n == m + 1 && n < d, b[n - 1], If[n == m - 3 || n == m + 3, If[n == m - 3 && m == d, c[m - 3], If[n == m + 3 && n == d, c[n - 3], 0]]]]]]] MO[d_] := Table[If[TrueQ[T[n, m, d] == Null], 0, T[n, m, d]], {n, 1, d}, {m, 1, d}]; a1 = Join[{{1}}, Table[CoefficientList[CharacteristicPolynomial[MO[n], x], x], {n, 1, 12}]]' Flatten[a1]

CROSSREFS

Cf. A129844.

Adjacent sequences: A136597 A136598 A136599 this_sequence A136601 A136602 A136603

Sequence in context: A105537 A115237 A105542 this_sequence A136672 A097750 A133544

KEYWORD

uned,tabl,sign

AUTHOR

Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Mar 24 2008

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Last modified January 7 17:35 EST 2009. Contains 152824 sequences.


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