%I A060423
%S A060423 0,0,0,0,0,5,6,21,24,54,60,110,120,195,210,315,336,476,504,684,720,945,
%T A060423 990,1265,1320,1650,1716,2106,2184,2639,2730,3255,3360,3960,4080,4760,
%U A060423 4896,5661,5814,6669,6840,7790,7980,9030,9240,10395,10626
%N A060423 Number of obtuse triangles made from vertices of a regular n-gon.
%F A060423 n(n-1)(n-3)/8 when n odd; n(n-2)(n-4)/8 when n even
%F A060423 G.f.: x^5(x+5)/((1-x)(1-x^2)^3). - Michael Somos, Jan 30 2004
%F A060423 For n odd, a(n) = A080838(n). [From Gerald McGarvey (gerald.mcgarvey(AT)comcast.net), 
               Sep 14 2008]
%o A060423 (PARI) a(n)=polcoeff(x^5*(5+x)/(1-x)/(1-x^2)^3+x*O(x^n),n)
%Y A060423 Cf. A007290, A046092, A000330.
%Y A060423 Sequence in context: A133608 A072577 A057520 this_sequence A037951 A095308 
               A132796
%Y A060423 Adjacent sequences: A060420 A060421 A060422 this_sequence A060424 A060425 
               A060426
%K A060423 easy,nice,nonn
%O A060423 0,6
%A A060423 Sen-Peng You (giawgwan(AT)single.url.com.tw), Apr 05 2001