Integer quartets a(4k)= 2, a(4k+1) = 32*k^2-24*k+3, a(4k+2) = 32*k^2-24*k+2, a(4k+3) = 8*k-3, k>=1.

Terms

a(0) =2a(1) =11a(2) =10a(3) =5a(4) =2a(5) =83a(6) =82a(7) =13a(8) =2a(9) =219a(10) =218a(11) =21a(12) =2a(13) =419a(14) =418a(15) =29a(16) =2a(17) =683a(18) =682a(19) =37a(20) =2a(21) =1011a(22) =1010a(23) =45a(24) =2a(25) =1403a(26) =1402a(27) =53a(28) =2a(29) =1859