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.

Previous Showing 11-15 of 15 results.

A331922 Number of compositions (ordered partitions) of n into distinct Lucas numbers (beginning with 1).

Original entry on oeis.org

1, 1, 0, 1, 3, 2, 0, 3, 8, 0, 2, 9, 8, 0, 8, 32, 6, 0, 9, 32, 0, 8, 38, 30, 0, 32, 150, 0, 6, 33, 32, 0, 32, 158, 30, 0, 38, 174, 0, 30, 176, 150, 0, 150, 870, 24, 0, 33, 152, 0, 32, 182, 150, 0, 158, 894, 0, 30, 182, 174, 0, 174, 1014, 144, 0, 176, 990, 0, 150, 1014, 864
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 01 2020

Keywords

Examples

			a(7) = 3 because we have [7], [4, 3] and [3, 4].
		

Crossrefs

Cf. A000204, A003263, A054770 (positions of 0's), A067592, A067595, A218396, A288039.

A332529 Rectangular array by antidiagonals: T(n,k) = floor(n + k*r), where r = golden ratio = (1+sqrt(5))/2.

Original entry on oeis.org

0, 2, 1, 5, 3, 2, 7, 6, 4, 3, 10, 8, 7, 5, 4, 13, 11, 9, 8, 6, 5, 15, 14, 12, 10, 9, 7, 6, 18, 16, 15, 13, 11, 10, 8, 7, 20, 19, 17, 16, 14, 12, 11, 9, 8, 23, 21, 20, 18, 17, 15, 13, 12, 10, 9, 26, 24, 22, 21, 19, 18, 16, 14, 13, 11, 10, 28, 27, 25, 23, 22
Offset: 0

Views

Author

Clark Kimberling, Jun 15 2020

Keywords

Comments

Column 0: Nonnegative integers.
Row 0: Upper Wythoff sequence, A001950, with 0 prepended.
Main Diagonal: A003231, with 0 prepended.
Diagonal (2,6,9,13,...) = A054770.
Diagonal (1,4,8,11,...) = A214971.
Diagonal (2,5,9,12,...) = A284624.

Examples

			Northwest corner:
  0   2    5    7   10   13   15
  1   3    6    8   11   14   16
  2   4    7    9   12   15   17
  3   5    8   10   13   16   18
  4   6    9   11   14   17   19
  5   7   10   12   15   18   20
  6   8   11   13   16   19   21
As a triangle (antidiagonals):
  0
  1   2
  2   3   5
  3   4   6   7
  4   5   7   8  10
		

Crossrefs

Programs

  • Mathematica
    t[n_, k_] := Floor[n + k*GoldenRatio];
    Grid[Table[t[n, k], {n, 0, 10}, {k, 0, 10}]] (* A332529 array *)
    Table[t[n - k, k], {n, 0, 12}, {k, n, 0, -1}] // Flatten  (* A332529 sequence *)

Formula

T(n,k) = floor(n + k*r), where r = (golden ratio)^2 = (3+sqrt(5))/2.

Extensions

Definition corrected by Harvey P. Dale, Jun 14 2022

A104857 Positive integers that cannot be represented as the sum of distinct Lucas 3-step numbers (A001644).

Original entry on oeis.org

2, 5, 6, 9, 13, 16, 17, 20, 23, 26, 27, 30, 34, 37, 38, 41, 44, 45, 48, 52, 55, 56, 59, 62, 65, 66, 69, 73, 76, 77, 80, 84, 87, 88, 91, 94, 97, 98, 101, 105, 108, 109, 112, 115, 116, 119, 123, 126, 127, 130, 133, 136, 137, 140, 144, 147, 148, 151, 154
Offset: 1

Views

Author

Jonathan Vos Post, Apr 24 2005

Keywords

Comments

Similar to A054770 "Numbers that are not the sum of distinct Lucas numbers (A000204)" but with Lucas 3-step numbers (A001644). Wanted: equivalent of David W. Wilson conjecture (A054770) as proved by Ian Agol. Note that all positive integers can be presented as the sum of distinct Fibonacci numbers in A000119 way. Catalani called Lucas 3-step numbers "generalized Lucas numbers" but that is quite ambiguous. These are also called tribonacci-Lucas numbers.

Examples

			In "base Lucas 3-step numbers" we can represent 1 as "1", but cannot represent 2 because there is no next Lucas 3-step number until 3 and we can't have two instances of 1 summed here. We can represent 3 as "10" (one 3 and no 1's), 4 as "11" (one 3 and one 1). Then we cannot represent 5 or 6 because there is no next Lucas 3-step number until 7 and we can't sum two 3s or six 1's. 7 becomes "100" (one 7, no 3s and no 1's), 8 becomes "101" and so forth.
		

Crossrefs

Extensions

More terms from T. D. Noe, Apr 26 2005

A301653 Expansion of x*(1 + 2*x)/((1 - x)*(1 + x)*(1 - x - x^2)).

Original entry on oeis.org

0, 1, 3, 5, 10, 16, 28, 45, 75, 121, 198, 320, 520, 841, 1363, 2205, 3570, 5776, 9348, 15125, 24475, 39601, 64078, 103680, 167760, 271441, 439203, 710645, 1149850, 1860496, 3010348, 4870845, 7881195, 12752041, 20633238, 33385280, 54018520, 87403801, 141422323, 228826125, 370248450
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 25 2018

Keywords

Comments

Apparently (for n > 0), numbers that have a unique partition into a sum of distinct Lucas numbers (A000204).

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[x (1 + 2 x)/((1 - x) (1 + x) (1 - x - x^2)) , {x, 0, 40}], x]
    LinearRecurrence[{1, 2, -1, -1}, {0, 1, 3, 5}, 41]
    Table[LucasL[n + 1] - (3 - (-1)^n)/2, {n, 0, 40}]
    Table[Floor[GoldenRatio^(n + 1)] - 1, {n, 0, 40}]
  • PARI
    a(n) = fibonacci(n) + fibonacci(n+2) + ((-1)^n - 3)/2; \\ Altug Alkan, Mar 25 2018

Formula

G.f.: x*(1 + 2*x)/((1 - x)*(1 + x)*(1 - x - x^2)).
a(n) = a(n-1) + 2*a(n-2) - a(n-3) - a(n-4).
a(n) = Lucas(n+1) - (3 - (-1)^n)/2.
a(n) = floor(phi^(n+1)) - 1, where phi = (1 + sqrt(5))/2 is the golden ratio (A001622).
a(n) = Sum_{k>=0} A051601(n-k,k) (conjectured). - Greg Dresden, May 18 2023

A306683 Integers k for which the base-phi representation of k does not include 1 or phi.

Original entry on oeis.org

3, 5, 7, 10, 12, 14, 16, 18, 21, 23, 25, 28, 30, 32, 34, 36, 39, 41, 43, 45, 47, 50, 52, 54, 57, 59, 61, 63, 65, 68, 70, 72, 75, 77, 79, 81, 83, 86, 88, 90, 92, 94, 97, 99, 101, 104, 106, 108, 110, 112, 115, 117, 119, 121, 123, 126, 128, 130, 133, 135, 137, 139, 141, 144
Offset: 1

Views

Author

Michel Dekking, May 06 2019

Keywords

Comments

Let b = A214970 be the sequence of the integers k for which the base phi representation includes 1, and let c be the sequence of integers k for which the base phi representation includes phi.
Note that a, b and c form a complementary triple (since consecutive digits 11 do not occur in a base phi representation).
Conjecture (Moses 2012/Baruchel 2018): b is the generalized Beatty sequence b(n) = floor(n*phi) + 2*n + 1.
Conjecture (Kimberling 2012): c = A054770 = A000201(n) + 2*n - 1 = floor(n*phi) + 2*n - 1.
One can prove that the Moses/Baruchel conjecture and the Kimberling conjecture are equivalent.
Conjecture: (a(n)) is a union of two generalized Beatty sequences v and w, given by v(n) = floor(n*phi) + 2*n = A003231(n), and w(n) = 3*floor(n*phi) + n + 1 = A190509(n) + 1.
This conjecture is compatible with the Moses/Baruchel/Kimberling conjecture.
These three conjectures are proved in my paper 'Base phi representations and golden mean beta-expansions'. - Michel Dekking, Jun 26 2019

Examples

			3 = phi^2 + phi^{-2}, 5 = phi^3 + phi^{-1} + phi^{-4}.
		

Crossrefs

Previous Showing 11-15 of 15 results.