a(n) = n^4+4 = (n^2-2*n+2)*(n^2+2*n+2) = ((n-1)^2+1)*((n+1)^2+1).

Terms

a(0) =4a(1) =5a(2) =20a(3) =85a(4) =260a(5) =629a(6) =1300a(7) =2405a(8) =4100a(9) =6565a(10) =10004a(11) =14645a(12) =20740a(13) =28565a(14) =38420a(15) =50629a(16) =65540a(17) =83525a(18) =104980a(19) =130325a(20) =160004a(21) =194485a(22) =234260a(23) =279845a(24) =331780a(25) =390629a(26) =456980a(27) =531445a(28) =614660a(29) =707285