A280343 - OEIS

%I #13 Jan 03 2017 02:35:36

%S 1,25,81,233,401,585,1009,1289,1681,2377,2913,3353,4497,5033,5793,

%T 7097,8065,8761,10721,11513,12961,14873,16113,17065,19873,21225,22689,

%U 25465,27585,28793,32561,33865,36113,39177,41121,43481,48801,50361,52529,56201,59793

%N Number of 2 X 2 matrices with all elements in {-n,..,0,..,n} with determinant = 2*permanent.

%H Indranil Ghosh and Chai Wah Wu, <a href="/A280343/b280343.txt">Table of n, a(n) for n = 0..10000</a> (terms n = 0..145 from Indranil Ghosh)

%o (Python)

%o def t(n):

%o     s=0

%o     for a in range(-n,n+1):

%o         for b in range(-n,n+1):

%o             for c in range(-n,n+1):

%o                 for d in range(-n,n+1):

%o                     if (a*d-b*c)==2*(a*d+b*c):

%o                         s+=1

%o     return s

%o for i in range(0,146):

%o     print str(i)+" "+str(t(i))

%Y Cf. A016754 (Number of 2 X 2 matrices with all elements in {0,..,n} with determinant = 2* permanent).

%K nonn

%O 0,2

%A _Indranil Ghosh_, Jan 01 2017