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1,3
Table of n, a(n) for n=1..8.
Eric Weisstein's World of Mathematics, Hamiltonian Cycle
Eric Weisstein's World of Mathematics, Triangular Graph
Sequence in context: A012599 A247859 A202629 * A180127 A091804 A012853
Adjacent sequences: A129346 A129347 A129348 * A129350 A129351 A129352
nonn,more
Eric W. Weisstein, Apr 10 2007
a(6) from Alois P. Heinz, Nov 29 2010
a(7)-a(8) from Eric W. Weisstein, Mar 31 2014
Missing factor of 2 applied to a(8) by Eric W. Weisstein, Apr 08 2014
approved