Indices of centered heptagonal numbers (A069099) which are also triangular numbers (A000217).

A253879

Indices of centered heptagonal numbers (A069099) which are also triangular numbers (A000217).

Terms

    a(0) =1a(1) =9a(2) =136a(3) =2160a(4) =34417a(5) =548505a(6) =8741656a(7) =139317984a(8) =2220346081a(9) =35386219305a(10) =563959162792

External references