# [Husk], <s>11</s> 9 bytes ΘṁṠe→ΘmΣN Outputs as an infinite list. [Try it online!][TIO-jhurmgfv] ΘṁṠe→ΘmΣN N Start with the natural numbers. mΣ Get the triangular numbers. Θ Prepend 0. ṁṠe→ Concatenate the pairs [n + 1, n] for each element. Θ Prepend 0. [Husk]: https://github.com/barbuz/Husk [TIO-jhurmgfv]: https://tio.run/##ARoA5f9odXNr///OmOG5geG5oGXihpLOmG3Oo07//w "Husk – Try It Online"