Stem نَسِي has 4 unique word forms and appears 7 times in the Quran.

Word Translation Occurrences
نَسِيتُ [I] forgot, I forgot 4
نَسِيتُمۡ you forgot 4
فَنَسِيتَهَاۖ but you forgot them 2
نَسِيتَ you forget 2
نَسِينَٰكُمۡۖ have forgotten you 2