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A282389 Number of squares in triangle-shaped polyominoes obtained by adding three identical polyominoes to the previous one, starting with one L-tetromino.

%I A282389 #16 Apr 25 2018 11:49:56
%S A282389 4,10,25,70,238,901,3445,13390,52942,210226,838450,3350725,13393093,
%T A282389 53547790,214151950,856558645,3426077749,13703917774,54815043790,
%U A282389 219258602290,877031899954,3508124454085,14032487779525,56129938535185,224519713993489,898078755310654
%N A282389 Number of squares in triangle-shaped polyominoes obtained by adding three identical polyominoes to the previous one, starting with one L-tetromino.
%C A282389 Each polyomino a(n) has a width of A282390(n+1) squares and a height of A000051(n) squares.
%H A282389 Daniel Poveda Parrilla, <a href="/A282389/a282389.gif">Illustration of initial terms</a>
%F A282389 a(0) = 4; a(n) = a(n-1) + 3*(A282390(n)*A000051(n-1) - a(n-1)) for n > 0.
%F A282389 a(n) = A282390(n+(n mod 2))*A000051(n-(n mod 2)) for n > 0.
%F A282389 a(n) = (A282390(n+(n mod 2)) - A000051(n-1+(n mod 2)))*A000051(n-(n mod 2)) + A028401(n+2) for n > 0.
%o A282389 (Python)
%o A282389 m = [3, 1]
%o A282389 for i in range(25):
%o A282389     w, h = m[0], len(m)
%o A282389     print(sum(m)) # print(w) for widths of the polyominoes
%o A282389     m2 = [w-x for x in reversed(m) if w>x]
%o A282389     m = [w+x for x in m2] + [w for x in m if x==w] + m2
%o A282389 # _Andrey Zabolotskiy_, Feb 14 2017
%Y A282389 Cf. A000051, A028401, A282390.
%K A282389 nonn
%O A282389 0,1
%A A282389 _Daniel Poveda Parrilla_, Feb 14 2017