cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A367301 Triangular array T(n,k), read by rows: coefficients of strong divisibility sequence of polynomials p(1,x) = 1, p(2,x) = 3 + 3*x, p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where u = p(2,x), v = 1 - 2*x - x^2.

Original entry on oeis.org

1, 3, 3, 10, 16, 8, 33, 75, 63, 21, 109, 320, 380, 220, 55, 360, 1296, 1980, 1620, 720, 144, 1189, 5070, 9459, 9940, 6255, 2262, 377, 3927, 19353, 42615, 54561, 44085, 22635, 6909, 987, 12970, 72532, 184034, 277480, 272854, 179972, 78230, 20672, 2584
Offset: 1

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Author

Clark Kimberling, Dec 23 2023

Keywords

Comments

Because (p(n,x)) is a strong divisibility sequence, for each integer k, the sequence (p(n,k)) is a strong divisibility sequence of integers.

Examples

			First eight rows:
     1
     3      3
    10     16      8
    33     75     63     21
   109    320    380    220     55
   360   1296   1980   1620    720    144
  1189   5070   9459   9940   6255   2262   377
  3927  19353  42615  54561  44085  22635  6909  987
Row 4 represents the polynomial p(4,x) = 33 + 75*x + 63*x^2 + 21*x^3, so (T(4,k)) = (33,75,63,21), k=0..3.
		

Crossrefs

Cf. A006190 (column 1); A001906 (p(n,n-1)); A154244 (row sums, p(n,1)); A077957 (alternating row sums, p(n,-1)); A190984 (p(n,2)); A006190 (signed, p(n,-2)); A154244 (p(n,-3)); A190984 (p(n,-4)); A094440, A367208, A367209, A367210, A367211, A367297, A367298, A367299, A367300.

Programs

  • Mathematica
    p[1, x_] := 1; p[2, x_] := 3 + 3 x; u[x_] := p[2, x]; v[x_] := 1 - 2 x - x^2;
    p[n_, x_] := Expand[u[x]*p[n - 1, x] + v[x]*p[n - 2, x]]
    Grid[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]
    Flatten[Table[CoefficientList[p[n, x], x], {n, 1, 10}]]

Formula

p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where p(1,x) = 1, p(2,x) = 3 + 3*x, u = p(2,x), and v = 1 - 2*x - x^2.
p(n,x) = k*(b^n - c^n), where k = -(1/sqrt(13 + 10*x + 5*x^2)), b = (1/2) (3*x + 3 + 1/k), c = (1/2) (3*x + 3 - 1/k).