Hexagonal numbers (A000384) which are also centered hexagonal numbers (A003215).

A006244

Hexagonal numbers (A000384) which are also centered hexagonal numbers (A003215).

Terms

    a(0) =1a(1) =91a(2) =8911a(3) =873181a(4) =85562821a(5) =8384283271a(6) =821574197731

External references