Number of positive solutions to (x_1)^2 + (x_2)^2 + (x_3)^2 + (x_4)^2 <= n^2.

Terms

a(0) =1a(1) =5a(2) =32a(3) =94a(4) =219a(5) =437a(6) =804a(7) =1362a(8) =2177a(9) =3271a(10) =4768a(11) =6708a(12) =9227a(13) =12381a(14) =16254a(15) =20954a(16) =26707a(17) =33461a(18) =41480a(19) =50884a(20) =61703a(21) =74183a(22) =88606a(23) =104862a(24) =123481a(25) =144241a(26) =167604a(27) =193648a(28) =222799a(29) =254731