Every character on Jiǎoluò Shūwū read as nian in any tone — 2 readings total across the four tones. Pick the tone you mean.
If you have the sound nian but not the character, here are the 2 characters read this way: 年 (nián, year), 念 (niàn, to recite, to keep in mind, to miss). They split across 2 tones, so the tone is what separates them.