166668domain: NAppears in sequencesNumbers k such that k^2 is the concatenation of two numbers m and 8*m.at n=9A115550Arises in enumerating non-degenerate colorings in Brook's Theorem.at n=18A152390Averages of twin prime pairs of A074378.at n=25A154563Numbers k such that k-1 | concat(k, k+1).at n=18A281233