Indices of triangular numbers which are also pentagonal.

A046175

Indices of triangular numbers which are also pentagonal.

Terms

    a(0) =0a(1) =1a(2) =20a(3) =285a(4) =3976a(5) =55385a(6) =771420a(7) =10744501a(8) =149651600a(9) =2084377905a(10) =29031639076a(11) =404358569165

External references