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See A195500 for discussion and list of related sequences; see A195568 for Mathematica program.
Table of n, a(n) for n=1..21.
Empirical g.f.: -x*(x^8-x^7-4*x^6-272*x^5+48*x^4-88*x^3-209*x^2-15*x-4) / (x^9-257*x^6-257*x^3+1). - Colin Barker, Jun 04 2015
Cf. A195500, A195568, A195570.
Sequence in context: A197934 A137654 A277509 * A118908 A153060 A139244
Adjacent sequences: A195566 A195567 A195568 * A195570 A195571 A195572
Clark Kimberling, Sep 21 2011