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URL: https://oeis.org/A156601

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A156601
Triangle T(n, k, m) = t(n, m)/(t(k, m)*t(n-k, m)), where t(n, k) = Product_{j=1..n} p(j, k+1), p(n, x) = Sum_{j=0..n} (-1)^j*A053122(n, j)*x^j, and m = 7, read by rows.
5
1, 1, 1, 1, -6, 1, 1, 35, 35, 1, 1, -204, 1190, -204, 1, 1, 1189, 40426, 40426, 1189, 1, 1, -6930, 1373295, -8004348, 1373295, -6930, 1, 1, 40391, 46651605, 1584821667, 1584821667, 46651605, 40391, 1, 1, -235416, 1584781276, -313786692648, 1828884203718, -313786692648, 1584781276, -235416, 1
OFFSET
0,5
FORMULA
T(n, k, m) = t(n, m)/(t(k, m)*t(n-k, m)), where t(n, k) = Product_{j=1..n} p(j, k+1), p(n, x) = Sum_{j=0..n} (-1)^j*A053122(n, j)*x^j, and m = 7.
EXAMPLE
Triangle begins as:
1;
1, 1;
1, -6, 1;
1, 35, 35, 1;
1, -204, 1190, -204, 1;
1, 1189, 40426, 40426, 1189, 1;
1, -6930, 1373295, -8004348, 1373295, -6930, 1;
1, 40391, 46651605, 1584821667, 1584821667, 46651605, 40391, 1;
MATHEMATICA
(* First program *)
b[n_, k_]:= If[k==n, 2, If[k==n-1 || k==n+1, -1, 0]];
M[d_]:= Table[b[n, k], {n, d}, {k, d}];
p[x_, n_]:= If[n==0, 1, CharacteristicPolynomial[M[n], x]];
f= Table[p[x, n], {n, 0, 20}];
t[n_, k_]:= If[k==0, n!, Product[f[[j]], {j, n}]/.x->(k+1)];
T[n_, k_, m_]:= If[n==0, 1, t[n, m]/(t[k, m]*t[n-k, m])];
Table[T[n, k, 7], {n, 0, 12}, {k, 0, n}]//TableForm (* modified by G. C. Greubel, Jun 25 2021 *)
(* Alternative: *)
t[n_, k_]:= t[n, k]= If[n==0, 1, If[k==0, (n-1)!, Product[(-1)^j*Simplify[ChebyshevU[j, x/2 - 1]], {j, 0, n-1}]/.x->(k+1)]];
T[n_, k_, m_]:= T[n, k, m]= t[n, m]/(t[k, m]*t[n-k, m]);
Table[T[n, k, 7], {n, 0, 12}, {k, 0, n}]//Flatten (* G. C. Greubel, Jun 25 2021 *)
PROG
(SageMath)
@CachedFunction
def t(n, k):
if (n==0): return 1
elif (k==0): return factorial(n-1)
else: return product( (-1)^j*chebyshev_U(j, (k-1)/2) for j in (0..n-1) )
def T(n, k, m): return t(n, m)/(t(k, m)*t(n-k, m))
flatten([[T(n, k, 7) for k in (0..n)] for n in (0..12)]) # G. C. Greubel, Jun 25 2021
CROSSREFS
Cf. A007318 (m=0), A034801 (m=4), A156599 (m=5), A156600 (m=6), this sequence (m=7), A156602 (m=8), A156603.
Cf. A053122.
Sequence in context: A176429 A157155 A022169 * A178232 A203338 A158116
KEYWORD
sign,tabl
AUTHOR
Roger L. Bagula, Feb 11 2009
EXTENSIONS
Edited by G. C. Greubel, Jun 25 2021
STATUS
approved