puzzle - Formula to this pattern? $1$, $11$, $21$, $1211$, $111221

next 1221Discover the ultimate urban living experience at 1221 Broadway Lofts, where modern luxury meets the vibrant energy of downtown. Our lofts in San Antonio offer a perfect blend of sleek desnVirtual channel 15.1, Cox 1011, Spectrum 1221. Use the TV schedules pages as a TV guide for KPBS, KPBS2, KPBS Create, and PBS Kids.