1,2

W. D. Wallis. Magic Graphs. Birkhäuser, (2001). Section 2.10.

A. Kotzig and A. Rosa, Magic Valuations of Finite Graphs, Canad. Math. Bull. v.13 (1970), pp. 451-461.

J. P. McSorley and J. A. Trono, On k-minimum and m-minimum Edge-Magic Injections of Graphs, Discrete Mathematics, Volume 310, Issue 1, 6 January 2010, Pages 56-69.

a(4)=11 because when forming an edge-magic injection of K_4 we must use at least the first 10 natural numbers {1,2,...10} since K_4 has a total of 10 vertices and edges. However this is not possible. But there is an edge-magic injection using the set {1,2,....11}\{4}, namely with {1,2,3,5} as the vertex labels.

See related sequence A129413 which concerns the smallest value of the magic sum of an edge-magic injection of K_n.

Sequence in context: A263260 A324773 A373189 * A390380 A059753 A256001

Adjacent sequences: A152679 A152680 A152681 * A152683 A152684 A152685

nonn,more

John P. McSorley, Dec 10 2008

approved