Number of quadruples [i,j,k,l] with all entries between 1 and n such that gcd(i,j) = gcd(k,l).

Terms

a(0) =1a(1) =10a(2) =51a(3) =132a(4) =373a(5) =590a(6) =1287a(7) =1992a(8) =3209a(9) =4402a(10) =7323a(11) =9004a(12) =13949a(13) =17558a(14) =22159a(15) =27696a(16) =38897a(17) =45018a(18) =60931a(19) =70100a(20) =83653a(21) =98142a(22) =126391a(23) =139928a(24) =170489a(25) =195170a(26) =228139a(27) =254428a(28) =311661a(29) =334886