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 A203989 Array: row n shows the coefficients of the characteristic polynomial of the n-th principal submatrix of {max(i,j)} (A051125). 3
 1, -1, -2, -3, 1, 3, 11, 6, -1, -4, -23, -35, -10, 1, 5, 39, 98, 85, 15, -1, -6, -59, -207, -308, -175, -21, 1, 7, 83, 374, 795, 798, 322, 28, -1, -8, -111, -611, -1694, -2475, -1806, -546, -36, 1, 9, 143, 930, 3185, 6149, 6633, 3696, 870, 45 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Let p(n)=p(n,x) be the characteristic polynomial of the n-th principal submatrix.  The zeros of p(n) are real, and they interlace the zeros of p(n+1).  See A202605 for a guide to related sequences. The characteristic polynomial seems be the recurrence relation given by p(n,x) = -x * p(n-1,x) + n * (-1)^(n-1) * sum_{i=0..n-1} x^i * binomial(2n-i-2,i). - Enrique Pérez Herrero, Jan 29 2013 REFERENCES (For references regarding interlacing roots, see A202605.) LINKS EXAMPLE Top of the array: 1... -1 -2... -3.... 1 3.... 11... 6... -1 -4... -23.. -35.. -10...1 5.... 39... 98... 85...15.. -1 MATHEMATICA f[i_, j_] := Max[i, j]; m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}] TableForm[m[6]] (* 6th principal submatrix *) Flatten[Table[f[i, n + 1 - i], {n, 1, 12}, {i, 1, n}]]  (* A051125 *) p[n_] := CharacteristicPolynomial[m[n], x]; c[n_] := CoefficientList[p[n], x] TableForm[Flatten[Table[p[n], {n, 1, 10}]]] Table[c[n], {n, 1, 12}] Flatten[%]              (* A203989 *) TableForm[Table[c[n], {n, 1, 10}]] CROSSREFS Cf. A051125, A202605. Cf. A181983, A076756. Sequence in context: A108990 A145080 A065078 * A126744 A122078 A126736 Adjacent sequences:  A203986 A203987 A203988 * A203990 A203991 A203992 KEYWORD tabl,sign AUTHOR Clark Kimberling, Jan 09 2012 STATUS approved

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Last modified September 22 03:20 EDT 2021. Contains 347605 sequences. (Running on oeis4.)