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.

Showing 1-3 of 3 results.

A291742 Number of maximal independent vertex sets in the n-Fibonacci cube graph.

Original entry on oeis.org

2, 2, 3, 7, 22, 123, 2281, 221074, 300492228
Offset: 1

Views

Author

Andrew Howroyd, Aug 30 2017

Keywords

Comments

The size of the smallest set, the independent domination number, is given by A291297.

Examples

			Case n=1: The vertices are 0, 1. Each singleton vertex set is a maximal independent set, so a(1) = 2.
Case n=2: The vertices are 00, 01, 10. Maximal independent sets are {00} and {01, 10}, so a(2) = 2.
Case n=3: The vertices are 000, 001, 010, 100, 101. Maximal independent sets are {000, 101}, {010, 101}, {001, 010, 100}, so a(3)=3.
		

Crossrefs

Programs

  • Python
    from itertools import combinations, product
    from networkx import empty_graph, find_cliques
    def A291742(n):
        v = tuple(int(q,2) for q in (''.join(p) for p in product('01',repeat=n)) if '11' not in q)
        G = empty_graph(v)
        e = tuple((a,b) for a, b in combinations(v,2) if (lambda m: (m&-m)^m if m else 1)(a^b))
        G.add_edges_from(e)
        return sum(1 for c in find_cliques(G)) # Chai Wah Wu, Jan 14 2024

Extensions

a(9) from Pontus von Brömssen, Mar 06 2020

A321684 Independent domination number of the n X n grid graph.

Original entry on oeis.org

0, 1, 2, 3, 4, 7, 10, 12, 16, 21, 24, 30, 35, 40, 47, 53, 60, 68, 76, 84, 92, 101, 111, 121, 131, 141, 152, 164, 176, 188, 200, 213, 227, 241, 255, 269, 284, 300, 316, 332, 348, 365, 383, 401, 419, 437, 456, 476, 496, 516, 536, 557, 579, 601, 623, 645, 668
Offset: 0

Views

Author

Andrey Zabolotskiy, Jan 14 2019

Keywords

Crossrefs

Programs

  • Maple
    ogf := (-41*x^6 + 47*x^5 - x^3 - x^2 + 41*x - 47)/((x - 1)^3*(x^4 + x^3 + x^2 + x + 1)): ser := series(ogf, x, 44):
    (0,1,2,3,4,7,10,12,16,21,24,30,35,40), seq(coeff(ser, x, n), n=0..42); # Peter Luschny, Jan 14 2019
  • PARI
    concat(0, Vec(x*(1 + 2*x^4 - x^5 - x^6 + 2*x^7 + x^8 - 4*x^9 + 3*x^10 - 2*x^12 + x^13 + x^14 - 2*x^15 + 2*x^16 - 2*x^18 + x^19) / ((1 - x)^3*(1 + x + x^2 + x^3 + x^4)) + O(x^40))) \\ Colin Barker, Jan 14 2019

Formula

For n >= 14, a(n) = floor((n+2)^2 / 5 - 4).
a(n) = A104519(n+2), the domination number of the n X n grid graph, for all n except for n = 9, 11.
From Colin Barker, Jan 14 2019: (Start)
G.f.: x*(1 + 2*x^4 - x^5 - x^6 + 2*x^7 + x^8 - 4*x^9 + 3*x^10 - 2*x^12 + x^13 + x^14 - 2*x^15 + 2*x^16 - 2*x^18 + x^19) / ((1 - x)^3*(1 + x + x^2 + x^3 + x^4)).
a(n) = 2*a(n-1) - a(n-2) + a(n-5) - 2*a(n-6) + a(n-7) for n > 20.
(End)

A291298 Connected domination number of Fibonacci cube Gamma_n.

Original entry on oeis.org

1, 1, 2, 3, 5, 7, 10, 14, 22
Offset: 1

Views

Author

N. J. A. Sloane, Aug 30 2017

Keywords

Crossrefs

Showing 1-3 of 3 results.