%I #16 Oct 25 2023 00:27:55
%S 1,21,276,2925,27405,237336,1947792,15380937,118030185,886163135,
%T 6540715896,47626016970,343006888770,2448296039700,17345898649800,
%U 122131734269895,855420636763836,5964720367660956
%N Binomial coefficient C(3n,n-6).
%D M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 828.
%H Seiichi Manyama, <a href="/A004324/b004324.txt">Table of n, a(n) for n = 6..1000</a>
%H Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Two Enumerative Functions</a>.
%H M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
%t Table[Binomial[3n,n-6],{n,6,30}] (* _Harvey P. Dale_, Oct 20 2015 *)
%K nonn,easy
%O 6,2
%A _N. J. A. Sloane_