Triangular numbers n such that psi(n) is also a triangular number, where psi is the Dedekind psi function (A001615).

A292063

Triangular numbers n such that psi(n) is also a triangular number, where psi is the Dedekind psi function (A001615).

Terms

    a(0) =1a(1) =780a(2) =2775a(3) =5050a(4) =474825a(5) =681528a(6) =1727011a(7) =5286126a(8) =5911641a(9) =6604795a(10) =17325441a(11) =21612025a(12) =27799696a(13) =45025305a(14) =386767578a(15) =1538599128a(16) =2086160121a(17) =3679490220a(18) =5718242211a(19) =7092226351a(20) =8019794628a(21) =16505718895a(22) =36604197735a(23) =55541611986a(24) =56693041356a(25) =89369984476

External references