A128929 Diameter of a special type of regular graph of degree 4 whose order maintain an increase in form of an arithmetic progression.

1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21

Offset

4,3

References

Claude C.S. and Dinneen M.J (1998), Group-theoretic methods for designing networks, Discrete mathematics and theoretical computer science, Research report

Comellas, F. and Gomez, J. (1995), New large graphs with given degree and diameter, in Proceedings of the seventh quadrennial international conference on the theory and applications of graphs, Volume 1: pp. 222-233

Ibrahim, A., A. (2007), A stable variety of Cayley graphs (in preparation)

Links

Table of n, a(n) for n=4..84.

Eric Weisstein's World of Mathematics, Graph Thickness

Index entries for linear recurrences with constant coefficients, signature (1, 0, 0, 1, -1).

Formula

f(D4,5)=1: Order =4,5; f(D)= f(D4,5)+n: order=5+n, n=1,2,...

I am assuming this sequence is just Floor[(n+5)/4]... - Eric W. Weisstein, Sep 09 2008

Example

f(D4,5)=1 when order=4, f(D4,5)=1 when order=5, f(D)=f(D4,5)+1=1+1=2 when order is 5+1=6

Prog

(PARI) a(n)=(n+2)\4 \\ Charles R Greathouse IV, May 28 2026

Crossrefs

Cf. A123642.

First differences of A186347.

Sequence in context: A110655 A008621 A144075 * A257839 A075245 A367329

Adjacent sequences: A128926 A128927 A128928 * A128930 A128931 A128932

Keyword

nonn,easy

Author

Aminu Alhaji Ibrahim, Apr 25 2007

Status

approved