Triangular numbers of the form 2..21..1; n_times 2 followed with n_times 1; n >= 1.
A319170
Triangular numbers of the form 2..21..1; n_times 2 followed with n_times 1; n >= 1.
Terms
- a(0) =21a(1) =2211a(2) =222111a(3) =22221111a(4) =2222211111a(5) =222222111111
External references
- oeis: A319170