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%I #23 Dec 05 2016 05:00:30
%S 3,5,5,5,8,5,5,8,8,5,5,8,8,8,5,5,8,8,8,8,5,5,8,8,8,8,8,5,5,8,8,8,8,8,
%T 8,5,5,8,8,8,8,8,8,8,5,5,8,8,8,8,8,8,8,8,5,5,8,8,8,8,8,8,8,8,8,5,5,8,
%U 8,8,8,8,8,8,8,8,8,5,5,8,8,8,8,8,8,8,8,8,8,8,5,5,8,8,8,8,8,8,8,8,8,8,8,8,5
%N Number of neighbors of the n-th term in a full square array read by antidiagonals.
%C Apart from the first row and the first column, the rest of the elements are 8's.
%C For the same idea but for a right triangle see A278480; for an isosceles triangle see A278481; for a square spiral see A010731; and for a hexagonal spiral see A010722.
%H Robert Israel, <a href="/A278545/b278545.txt">Table of n, a(n) for n = 1..10000</a>
%F G.f. 3+x+8*x/(1-x)-3*(1+x)*Theta_2(0,sqrt(x))/(2*x^(1/8)) where Theta_2 is a Jacobi Theta function. - _Robert Israel_, Dec 04 2016
%e The corner of the square array begins:
%e 3,5,5,5,5,5,5,5,5,5,...
%e 5,8,8,8,8,8,8,8,8,...
%e 5,8,8,8,8,8,8,8,...
%e 5,8,8,8,8,8,8,...
%e 5,8,8,8,8,8,...
%e 5,8,8,8,8,...
%e 5,8,8,8,...
%e 5,8,8,...
%e 5,8,...
%e 5,...
%e ...
%p 3, seq(op([5,8$i,5]),i=0..20); # _Robert Israel_, Dec 04 2016
%Y Antidiagonal sums give 3 together with the elements > 2 of A017089.
%Y Cf. A010722, A010731, A274912, A274913, A278317, A278290, A278480, A278481.
%K nonn,tabl
%O 1,1
%A _Omar E. Pol_, Nov 23 2016