a(n) is the least k such that A188999(A188999(k)) = n*k, where A188999 is the bi-unitary sigma function, or 0 if no such k exists.

A318242

a(n) is the least k such that A188999(A188999(k)) = n*k, where A188999 is the bi-unitary sigma function, or 0 if no such k exists.

Terms

    a(0) =1a(1) =2a(2) =8a(3) =15a(4) =24a(5) =42a(6) =240a(7) =648a(8) =168a(9) =480a(10) =321408a(11) =4320a(12) =57120a(13) =103680a(14) =1827840a(15) =23591520a(16) =898128000a(17) =374250240

External references