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.

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A015108 Carlitz-Riordan q-Catalan numbers (recurrence version) for q=-11.

Original entry on oeis.org

1, 1, -10, -1231, 1636130, 23957879562, -3858392581773300, -6835385537899011365535, 133202313157282627679850238250, 28553099061411464607955930776882965774
Offset: 0

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Author

Keywords

Examples

			G.f. = 1 + x - 10*x^2 - 1231*x^3 + 1636130*x^4 + 23957879562*x^5 + ...
		

Crossrefs

Cf. A227543.
Cf. this sequence (q=-11), A015107 (q=-10), A015106 (q=-9), A015105 (q=-8), A015103 (q=-7), A015102 (q=-6), A015100 (q=-5), A015099 (q=-4), A015098 (q=-3), A015097 (q=-2), A090192 (q=-1), A000108 (q=1), A015083 (q=2), A015084 (q=3), A015085 (q=4), A015086 (q=5), A015089 (q=6), A015091 (q=7), A015092 (q=8), A015093 (q=9), A015095 (q=10), A015096 (q=11).
Column k=11 of A290789.

Programs

  • Mathematica
    m = 10; ContinuedFractionK[If[i == 1, 1, -(-11)^(i-2) x], 1, {i, 1, m}] + O[x]^m // CoefficientList[#, x]& (* Jean-François Alcover, Nov 17 2019 *)
  • Ruby
    def A(q, n)
      ary = [1]
      (1..n).each{|i| ary << (0..i - 1).inject(0){|s, j| s + q ** j * ary[j] * ary[i - 1 - j]}}
      ary
    end
    def A015108(n)
      A(-11, n)
    end # Seiichi Manyama, Dec 25 2016

Formula

a(n+1) = Sum_{i=0..n} q^i*a(i)*a(n-i) with q=-11 and a(0)=1.
G.f. satisfies: A(x) = 1 / (1 - x*A(-11*x)) = 1/(1-x/(1+11*x/(1-11^2*x/(1+11^3*x/(1-...))))) (continued fraction). - Seiichi Manyama, Dec 28 2016

Extensions

Offset changed to 0 by Seiichi Manyama, Dec 25 2016

A290759 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of continued fraction 1/(1 - x/(1 - k*x/(1 - k^2*x/(1 - k^3*x/(1 - k^4*x/(1 - ...)))))).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 5, 1, 1, 1, 4, 17, 14, 1, 1, 1, 5, 43, 171, 42, 1, 1, 1, 6, 89, 1252, 3113, 132, 1, 1, 1, 7, 161, 5885, 104098, 106419, 429, 1, 1, 1, 8, 265, 20466, 1518897, 25511272, 7035649, 1430, 1, 1, 1, 9, 407, 57799, 12833546, 1558435125, 18649337311, 915028347, 4862, 1
Offset: 0

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Author

Ilya Gutkovskiy, Aug 09 2017

Keywords

Comments

This is the transpose of the array in A090182.

Examples

			G.f. of column k: A_k(x) = 1 + x + (k + 1)*x^2 + (k^3 + k^2 + 2*k + 1)*x^3 + (k^6 + k^5 + 2*k^4 + 3*k^3 + 3*k^2 + 3*k + 1)*x^4 + ...
Square array begins:
  1,   1,     1,       1,        1,         1,  ...
  1,   1,     1,       1,        1,         1,  ...
  1,   2,     3,       4,        5,         6,  ...
  1,   5,    17,      43,       89,       161,  ...
  1,  14,   171,    1252,     5885,     20466,  ...
  1,  42,  3113,  104098,  1518897,  12833546,  ...
		

Crossrefs

Main diagonal gives A290777.

Programs

  • Maple
    A:= proc(n, k) option remember; `if`(n=0, 1, add(
          A(j, k)*A(n-j-1, k)*k^j, j=0..n-1))
        end:
    seq(seq(A(n, d-n), n=0..d), d=0..12);  # Alois P. Heinz, Aug 10 2017
  • Mathematica
    Table[Function[k, SeriesCoefficient[1/(1 - x/(1 + ContinuedFractionK[-k^i x, 1, {i, 1, n}])), {x, 0, n}]][j - n], {j, 0, 10}, {n, 0, j}] // Flatten
  • Python
    from sympy.core.cache import cacheit
    @cacheit
    def A(n, k): return 1 if n==0 else sum(A(j, k)*A(n - j - 1, k)*k**j for j in range(n))
    for n in range(13): print([A(k, n - k) for k in range(n + 1)]) # Indranil Ghosh, Aug 10 2017, after Maple code

Formula

G.f. of column k: 1/(1 - x/(1 - k*x/(1 - k^2*x/(1 - k^3*x/(1 - k^4*x/(1 - ...)))))), a continued fraction.

A290786 a(n) = n-th Carlitz-Riordan q-Catalan number (recurrence version) for q = -n.

Original entry on oeis.org

1, 1, -1, -23, 3429, 8425506, -412878084725, -497641562809372379, 17436260499054618815283977, 20503694883570579788445502041773422, -917439693541287252616828116888122637934368489, -1746281566732870051764961051797990328294109372786185933382
Offset: 0

Views

Author

Alois P. Heinz, Aug 10 2017

Keywords

Crossrefs

Main diagonal of A290789.
Cf. A290777.

Programs

  • Maple
    b:= proc(n, k) option remember; `if`(n=0, 1, add(
          b(j, k)*b(n-j-1, k)*(-k)^j, j=0..n-1))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..12);
  • Mathematica
    b[n_, k_]:=b[n, k]=If[n==0, 1, Sum[b[j, k] b[n - j - 1, k] (-k)^j, {j, 0, n - 1}]]; Table[b[n, n], {n, 0, 15}] (* Indranil Ghosh, Aug 10 2017 *)
  • Python
    from sympy.core.cache import cacheit
    @cacheit
    def b(n, k): return 1 if n==0 else sum([b(j, k)*b(n - j - 1, k)*(-k)**j for j in range(n)])
    def a(n): return b(n, n)
    print([a(n) for n in range(16)]) # Indranil Ghosh, Aug 10 2017

Formula

a(n) = [x^n] 1/(1-x/(1+n*x/(1-n^2*x/(1+n^3*x/(1-n^4*x/(1+ ... )))))).
a(n) = A290789(n,n).
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