18715702domain: NAppears in sequencesPowers of sqrt(21) rounded to nearest integer.at n=11A017968Powers of sqrt(21) rounded up.at n=11A017969Powers of fourth root of 21 rounded to nearest integer.at n=22A018106Powers of fourth root of 21 rounded up.at n=22A018107Nearest integer to n^(11/2).at n=21A036495