a(1) = 1, a(2) = 3; 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).

A308669

a(1) = 1, a(2) = 3; 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) =3a(2) =12a(3) =28a(4) =60a(5) =124a(6) =252a(7) =510a(8) =1032a(9) =2070a(10) =4146a(11) =8298a(12) =16602a(13) =33210a(14) =66426a(15) =132858a(16) =265722a(17) =531450a(18) =1062906a(19) =2125818a(20) =4251642a(21) =8503290a(22) =17006588a(23) =34013180a(24) =68026364a(25) =136052736a(26) =272105480a(27) =544210964a(28) =1088421932a(29) =2176843872

External references