891224domain: NAppears in sequencesPowers of sqrt(21) rounded to nearest integer.at n=9A017968Powers of sqrt(21) rounded up.at n=9A017969Powers of fourth root of 21 rounded to nearest integer.at n=18A018106Powers of fourth root of 21 rounded up.at n=18A018107Nearest integer to n^(9/2).at n=21A036494