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%I #8 May 02 2020 05:01:38
%S 0,0,24,102,252,504,867,1431,2214,3228,4509,6237,8481,11259,14445,
%T 18261,22935,28497,34980,42762,51708,61632,72795,85791,100611,117027,
%U 134874,154836,177402,202548,230355,261543,295707,332271,371313,413937,460881,511551
%N Number of quadrilateral regions in an equilateral triangular "frame" of size n (see Comments in A328526 for definition),
%C See A328526 for images of the triangular frame.
%H Lars Blomberg, <a href="/A333033/b333033.txt">Table of n, a(n) for n = 1..65</a>
%Y Cf. A328526 (regions), A333030 (edges), A333031 (vertices), A333032 (3-gons), A331776 (square frame), A274586 (filled triangle).
%K nonn
%O 1,3
%A _Scott R. Shannon_ and _N. J. A. Sloane_, Mar 05 2020
%E a(12) and beyond from _Lars Blomberg_, May 01 2020
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