Triangular numbers composed of digits {1,7,9}.
A119148
Triangular numbers composed of digits {1,7,9}.
Terms
- a(0) =1a(1) =91a(2) =171a(3) =1711a(4) =171991a(5) =791911a(6) =1717771191a(7) =911977119991a(8) =999999911791
External references
- oeis: A119148