Number of n X n arrays of squares of integers summing to 4.

Terms

a(0) =5a(1) =135a(2) =1836a(3) =12675a(4) =58941a(5) =211925a(6) =635440a(7) =1663821a(8) =3921325a(9) =8495531a(10) =17179020a(11) =32795295a(12) =59626581a(13) =103962825a(14) =174792896a(15) =284660665a(16) =450710325a(17) =695946991a(18) =1050740300a(19) =1554600411a(20) =2258257485a(21) =3226077405a(22) =4538848176a(23) =6296973125a(24) =8624108701a(25) =11671286355