a(1) = 1, a(2) = 2; for n > 1, a(n) = sum of the next two smallest integers > a(n-1) which are coprime to the sum s = a(1) + ... + a(n-1).

A131357

a(1) = 1, a(2) = 2; for n > 1, a(n) = sum of the next two smallest integers > a(n-1) which are coprime to the sum s = a(1) + ... + a(n-1).

Terms

    a(0) =1a(1) =2a(2) =9a(3) =24a(4) =54a(5) =120a(6) =248a(7) =500a(8) =1004a(9) =2016a(10) =4038a(11) =8082a(12) =16170a(13) =32346a(14) =64700a(15) =129404a(16) =258812a(17) =517644a(18) =1035294a(19) =2070594a(20) =4141194a(21) =8282394a(22) =16564800a(23) =33129608a(24) =66259220a(25) =132518444a(26) =265036896a(27) =530073798a(28) =1060147602a(29) =2120295210

External references