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 A104562 Inverse of the Motzkin triangle A064189. 13
 1, -1, 1, 0, -2, 1, 1, 1, -3, 1, -1, 2, 3, -4, 1, 0, -4, 2, 6, -5, 1, 1, 2, -9, 0, 10, -6, 1, -1, 3, 9, -15, -5, 15, -7, 1, 0, -6, 3, 24, -20, -14, 21, -8, 1, 1, 3, -18, -6, 49, -21, -28, 28, -9, 1, -1, 4, 18, -36, -35, 84, -14, -48, 36, -10, 1, 0, -8, 4, 60, -50, -98, 126, 6, -75, 45, -11, 1, 1, 4, -30, -20, 145, -36, -210, 168, 45, -110, 55 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Or, triangle read by rows: T(0,0)=1; for n>=1 T(n,k) is the coefficient of x^k in the monic characteristic polynomial of the n X n tridiagonal matrix with 1's on the main, sub- and superdiagonal (0<=k<=n). The characteristic polynomial has a root 1+2cos(Pi/(n+1)). - Gary W. Adamson, Nov 19 2006 Row sums have g.f. 1/(1+x^2); diagonal sums are (-1)^n. Riordan array (1/(1+x+x^2), x/(1+x+x^2)). Apart from signs, identical to A101950. Or, triangle read by rows in which row n gives coefficients of characteristic polynomial of tridiagonal matrix with 1's on the main diagonal and -1's on the two adjacent diagonals. For example: M(3)={{1, -1, 0}, {-1, 1, -1}, {0, -1, 1}}. - Roger L. Bagula, Mar 15 2008 Subtriangle of the triangle given by [0,-1,1,-1,0,0,0,0,0,0,0,...) DELTA [1,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938. - Philippe Deléham, Jan 27 2010 Triangle of coefficients of Chebyshev's S(n,x-1) polynomials (exponents of x in increasing order). - Philippe Deléham, Feb 19 2012 REFERENCES Anthony Ralston and Philip Rabinowitz, A First Course in Numerical Analysis, 1978, ISBN 0070511586, see p. 256. LINKS Paul Barry, Riordan-Bernstein Polynomials, Hankel Transforms and Somos Sequences, Journal of Integer Sequences, Vol. 15 2012, #12.8.2. A. Luzón, D. Merlini, M. A. Morón, R. Sprugnoli, Complementary Riordan arrays, Discrete Applied Mathematics, 172 (2014) 75-87. FORMULA T(n, k) = Sum_{j=0..n} (-1)^(k-j)*(-1)^((n-j)/2) C((n+j)/2, j)(1+(-1)^(n+j))C(j, k)/2. T(n,k) = (-1)^(n-k)*A101950(n,k). - Philippe Deléham, Feb 19 2012 T(n,k) = T(n-1,k-1) - T(n-1,k) - T(n-2,l). - Philippe Deléham, Feb 19 2012 A104562*A007318 = A049310 as infinite lower triangular matrices. - Philippe Deléham, Feb 19 2012 G.f.: 1/(1+x+x^2-y*x). - Philippe Deléham, Feb 19 2012 T(n,k) = (-1)^(n-k)*C(n,k)*hypergeom([(k-n)/2,(k-n+1)/2],[-n],4)) for n>=1. - Peter Luschny, Apr 25 2016 EXAMPLE Triangle starts: 1; -1,1; 0,-2,1; 1,1,-3,1; -1,2,3,-4,1; 0,-4,2,6,-5,1; Triangle [0,-1,1,-1,0,0,0,0,0,...] DELTA [1,0,0,0,0,0,0,0,...] begins : 1 ; 0,1 ; 0,-1,1 ; 0,0,-2,1 ; 0,1,1,-3,1 ; 0,-1,2,3,-4,1 ; ... - Philippe Deléham, Jan 27 2010 MAPLE with(linalg): m:=proc(i, j) if abs(i-j)<=1 then 1 else 0 fi end: T:=(n, k)->coeff(charpoly(matrix(n, n, m), x), x, k): 1; for n from 1 to 12 do seq(T(n, k), k=0..n) od; # yields sequence in triangular form # Alternatively: T := (n, k) -> `if`(n=0, 1, (-1)^(n-k)*binomial(n, k)*hypergeom([(k-n)/2, (k-n+1)/2], [-n], 4)): seq(seq(simplify(T(n, k)), k=0..n), n=0..10); # Peter Luschny, Apr 25 2016 MATHEMATICA a0[n_] := 1; b[n_] := -1; T[n_, m_, d_] := If[ n == m, a0[n], If[n == m - 1 || n == m + 1, If[n == m - 1, b[m - 1], If[n == m + 1, b[n - 1], 0]], 0]]; MO[d_] := Table[T[n, m, d], {n, 1, d}, {m, 1, d}]; a = Join[{{1}}, Table[CoefficientList[CharacteristicPolynomial[ MO[n], x], x], {n, 1, 10}]]; Flatten[a] (* Roger L. Bagula, Mar 15 2008 *) PROG (Sage) @CachedFunction def A104562(n, k):     if n< 0: return 0     if n==0: return 1 if k == 0 else 0     return A104562(n-1, k-1)-A104562(n-2, k)-A104562(n-1, k) for n in (0..9): [A104562(n, k) for k in (0..n)] # Peter Luschny, Nov 20 2012 (Sage) # Alternatively as coefficients of polynomials: def S(n, x):     if n==0: return 1     if n==1: return x-1     return (x-1)*S(n-1, x)-S(n-2, x) for n in (0..7): print(S(n, x).list()) # Peter Luschny, Jun 23 2015 CROSSREFS Cf. A125090, A101950. Sequence in context: A333381 A124094 A101950 * A164306 A309931 A309939 Adjacent sequences:  A104559 A104560 A104561 * A104563 A104564 A104565 KEYWORD easy,sign,tabl AUTHOR Paul Barry, Mar 15 2005 EXTENSIONS Edited by N. J. A. Sloane, Apr 10 2008 Typo correction in the Roger L. Bagula comment and Mathematica section by Wolfdieter Lang, Nov 22 2011 STATUS approved

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Last modified March 29 05:39 EDT 2020. Contains 333105 sequences. (Running on oeis4.)