a(n) = number of tuples (a,b,c,d) of natural numbers a,b,c,d <= n with gcd(a,b)=gcd(b,c)=gcd(c,d)=gcd(d,a)=1.

A256391

a(n) = number of tuples (a,b,c,d) of natural numbers a,b,c,d <= n with gcd(a,b)=gcd(b,c)=gcd(c,d)=gcd(d,a)=1.

Terms

    a(0) =1a(1) =7a(2) =35a(3) =79a(4) =243a(5) =319a(6) =787a(7) =1155a(8) =1859a(9) =2295a(10) =4267a(11) =4891a(12) =8295a(13) =9743a(14) =11851a(15) =14539a(16) =22191a(17) =24359a(18) =35427a(19) =39387a(20) =45915a(21) =51687a(22) =71171a(23) =76407a(24) =94911a(25) =105047a(26) =123251a(27) =134447a(28) =174003a(29) =180835

External references