Triangular numbers obtained as the concatenation of 2*k and k.
A226742
Triangular numbers obtained as the concatenation of 2*k and k.
Terms
- a(0) =21a(1) =105a(2) =2211a(3) =9045a(4) =222111a(5) =306153a(6) =742371a(7) =890445a(8) =1050525a(9) =22221111a(10) =88904445a(11) =107905395a(12) =173808690a(13) =2222211111a(14) =8889044445a(15) =12141260706a(16) =15754278771a(17) =222222111111a(18) =888890444445
External references
- oeis: A226742