0,2

A087457 gives number of odd length roads between any adjacent nodes in virtual optimal chordal ring of degree 3.

Given a(1)=1 and a(1)=2, then a(2)=4 since sum of first 3 coefficients of

A(x)^3=1+6x+24x^2+... equals 1+6+24 = 31 = A087457(3).

Cf. A087457, A088929.

Sequence in context: A117419 A124461 A026898 this_sequence A089844 A113997 A125789

Adjacent sequences: A088927 A088928 A088929 this_sequence A088931 A088932 A088933

nonn

Paul D. Hanna (pauldhanna(AT)juno.com), Oct 24 2003