# [Tcl], 77 bytes set j -1 time {set i -2 time {puts [expr [incr i]|$j?"$i $j":""]} 3 incr j} 3 [Try it online!][TIO-jh6qgqtx] [Tcl]: http://tcl.tk/ [TIO-jh6qgqtx]: https://tio.run/##K0nO@f@/OLVEIUtB15CrJDM3VaEaxM1U0DWCcgtKS4oVolMrCooUojPzkosUMmNrVLLslVQyFVSylKyUlGJrFYy5wDJZQNb//wA "Tcl – Try It Online"