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%I #7 Jun 25 2021 23:14:47
%S 1,1,1,1,-5,1,1,24,24,1,1,-115,552,-115,1,1,551,12673,12673,551,1,1,
%T -2640,290928,-1394030,290928,-2640,1,1,12649,6678672,153331178,
%U 153331178,6678672,12649,1,1,-60605,153318529,-16865038190,80805530806,-16865038190,153318529,-60605,1
%N 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 = 6, read by rows.
%H G. C. Greubel, <a href="/A156600/b156600.txt">Rows n = 0..50 of the triangle, flattened</a>
%F 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 = 6.
%e Triangle begins as:
%e 1;
%e 1, 1;
%e 1, -5, 1;
%e 1, 24, 24, 1;
%e 1, -115, 552, -115, 1;
%e 1, 551, 12673, 12673, 551, 1;
%e 1, -2640, 290928, -1394030, 290928, -2640, 1;
%e 1, 12649, 6678672, 153331178, 153331178, 6678672, 12649, 1;
%t (* First program *)
%t b[n_, k_]:= If[k==n, 2, If[k==n-1 || k==n+1, -1, 0]];
%t M[d_]:= Table[b[n, k], {n,d}, {k,d}];
%t p[x_, n_]:= If[n==0, 1, CharacteristicPolynomial[M[n], x]];
%t f= Table[p[x, n], {n,0,20}];
%t t[n_, k_]:= If[k==0, n!, Product[f[[j]], {j, n}]/.x->(k+1)];
%t T[n_, k_, m_]:= If[n==0, 1, t[n, m]/(t[k, m]*t[n-k, m])];
%t Table[T[n, k, 6], {n,0,12}, {k,0,n}]//TableForm (* modified by _G. C. Greubel_, Jun 25 2021 *)
%t (* Second program *)
%t 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 T[n_, k_, m_]:= T[n, k, m]= t[n, m]/(t[k, m]*t[n-k, m]);
%t Table[T[n, k, 6], {n,0,12}, {k,0,n}]//Flatten (* _G. C. Greubel_, Jun 25 2021 *)
%o (Sage)
%o @CachedFunction
%o def t(n, k):
%o if (n==0): return 1
%o elif (k==0): return factorial(n-1)
%o else: return product( (-1)^j*chebyshev_U(j, (k-1)/2) for j in (0..n-1) )
%o def T(n,k,m): return t(n,m)/(t(k,m)*t(n-k,m))
%o flatten([[T(n, k, 6) for k in (0..n)] for n in (0..12)]) # _G. C. Greubel_, Jun 25 2021
%Y Cf. A007318 (m=0), A034801 (m=4), A156599 (m=5), this sequence (m=6), A156601 (m=7), A156602 (m=8), A156603.
%Y Cf. A053122.
%K sign,tabl
%O 0,5
%A _Roger L. Bagula_, Feb 11 2009
%E Edited by _G. C. Greubel_, Jun 25 2021
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