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A109646 Triangle, read by rows, of the number of different isotemporal classes of rotationally distinct diasters with n (rows) total peripheral edges with k (columns) peripheral edges on one side.

%I A109646 #3 Feb 27 2009 03:00:00
%S A109646 1,1,1,3,1,6,1,8,6,1,10,12,1,12,15,10,1,14,18,20,1,16,21,24,15,1,18,
%T A109646 24,28,30,1,20,27,32,35,21,1,22,30,36,40,42,1,24,33,40,45,48,28,1,26,
%U A109646 36,44,50,54,56,1,28,39,48,55,60,63,36,1,30,42,52,60,66,70,72,1,32,45,56,65
%N A109646 Triangle, read by rows, of the number of different isotemporal classes of rotationally distinct diasters with n (rows) total peripheral edges with k (columns) peripheral edges on one side.
%C A109646 See A092481 for the definition of isotemporal class. A109622 is the sum of rows.
%D A109646 B. de Bivort. Isotemporal classes of diasters, beachballs and daisies. Preprint, 2005.
%F A109646 for k=0, a(n, k)=1 for k>0 and n!=k, a(n, k)=(n-k)k+(n-k)+k+1 for k>0 and n=k, a(n, k)=(1/2)(k^2+3k+2)
%e A109646 Row 0 has 1 element, a diaster with no peripheral edges - a singleton edge - for which there is only a single isotemporal class. Row 1 has 1 element, the diaster with a single peripheral edge - two edges sharing a single vertex - for which there is a single isotemporal class. Row 2 has 2 elements, corresponding to the diaster with a two peripheral edges on a single side and the diaster with a single peripheral edge on either side, with 1 and 3 isotemporal classes respectively.
%Y A109646 Cf. A092481, A109622.
%K A109646 easy,nonn,tabf
%O A109646 0,4
%A A109646 Benjamin de Bivort (bivort(AT)fas.harvard.edu), Aug 04 2005