1,1
Table of n, a(n) for n=1..5.
Eric Weisstein's World of Mathematics, Apollonian Network
Eric Weisstein's World of Mathematics, Spanning Tree
Sequence in context: A221607 A160251 A106176 * A223101 A086815 A180504
Adjacent sequences: A193125 A193126 A193127 * A193129 A193130 A193131
nonn
Eric W. Weisstein, Jul 16 2011
approved