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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A296006 Decimal expansion of the limiting ratio of terms in A296005.

Original entry on oeis.org

3, 1, 1, 4, 9, 8, 6, 4, 4, 7, 3, 9, 0, 3, 0, 2, 2, 4, 0, 2, 1, 1, 6, 2, 7, 0, 8, 7, 5, 5, 5, 4, 0, 3, 2, 8, 8, 3, 6, 0, 0, 9, 2, 9, 4, 5, 6, 0, 5, 9, 4, 2, 0, 4, 1, 3, 8, 8, 0, 8, 6, 4, 2, 5, 5, 2, 0, 9, 6, 6, 0, 7, 0, 5, 7, 3, 1, 7, 7, 4, 7, 9, 9, 6, 6, 2
Offset: 1

Views

Author

Clark Kimberling, Dec 07 2017

Keywords

Comments

A296005(n)/A296005(n-1) -> 3.114986447390302...
See A296000 for a guide to related sequences and limiting ratios.

Crossrefs

Programs

  • Mathematica
    mex[list_] := NestWhile[# + 1 &, 1, MemberQ[list, #] &];
    a[0] = 2; a[1] = 3; b[0] = 1;
    a[n_] := a[n] = Sum[a[k]*b[n - k - 1], {k, 0, n - 1}];
    b[n_] := b[n] = mex[Flatten[Table[Join[{a[n]}, {a[i], b[i]}], {i, 0, n - 1}]]];
    Table[a[n], {n, 0, 100}];  (* A296005 *)
    t = N[Table[a[n]/a[n - 1], {n, 1, 500, 100}], 200]
    Take[RealDigits[Last[t], 10][[1]], 100]  (* A296006 *)

A296000 Solution of the complementary equation a(n) = a(0)*b(n-1) + a(1)*b(n-2) + ... + a(n-1)*b(0), where a(0) = 1, a(1) = 3, b(0) = 2, and (a(n)) and (b(n)) are increasing complementary sequences.

Original entry on oeis.org

1, 3, 10, 37, 135, 493, 1800, 6572, 23996, 87614, 319895, 1167997, 4264577, 15570774, 56851829, 207576737, 757901769, 2767242128, 10103722287, 36890593353, 134694505577, 491795012865, 1795636233585, 6556206140806, 23937943641806, 87401941533192
Offset: 0

Views

Author

Clark Kimberling, Dec 04 2017

Keywords

Comments

The increasing complementary sequences a() and b() are uniquely determined by the titular equation and initial values. a(n)/a(n-1) -> 3.651188... (as in A295999). Guide for the complementary equation a(n) = a(0)*b(n-1) + a(1)*b(n-2) + ... + a(n-1)*b(0):
A296000: a(0) = 1, a(1) = 3, b(0) = 2, limiting ratio of a(n)/a(n-1): A295999
A296001: a(0) = 1, a(1) = 2, b(0) = 3, limiting ratio of a(n)/a(n-1): A296002
A296003: a(0) = 2, a(1) = 4, b(0) = 1, limiting ratio of a(n)/a(n-1): A296004
A296005: a(0) = 2, a(1) = 3, b(0) = 1, limiting ratio of a(n)/a(n-1): A296006

Examples

			a(0) = 1, a(1) = 3, b(0) = 2, b(1) = 4, so that
a(2) = a(0)*b(1) + a(1)*b(0) = 10
Complement: (b(n)) = (2, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, ...)
		

Crossrefs

Programs

  • Mathematica
    $RecursionLimit = Infinity;
    mex[list_] := NestWhile[# + 1 &, 1, MemberQ[list, #] &];
    a[0] = 1; a[1] = 3; b[0] = 2; a[n_] := a[n] = Sum[a[k]*b[n - k - 1], {k, 0, n - 1}];
    b[n_] := b[n] = mex[Flatten[Table[Join[{a[n]}, {a[i], b[i]}], {i, 0, n - 1}]]];
    Table[a[n], {n, 0, 100}]  (* A296000 *)
    t = N[Table[a[n]/a[n - 1], {n, 1, 500, 100}], 200]
    Take[RealDigits[Last[t], 10][[1]], 100]  (* A295999 *)

Extensions

Incorrect conjectured g.f. removed by Georg Fischer, Sep 23 2020
Showing 1-2 of 2 results.