Indices of heptagonal numbers (A000566) which are also triangular numbers (A000217).

A046193

Indices of heptagonal numbers (A000566) which are also triangular numbers (A000217).

Terms

    a(0) =1a(1) =5a(2) =221a(3) =1513a(4) =71065a(5) =487085a(6) =22882613a(7) =156839761a(8) =7368130225a(9) =50501915861

External references