500002domain: NAppears in sequencesNumbers n such that n concatenated with n+1 is triangular.at n=22A094609Smallest sequence which lists the position of digits "4" in the sequence.at n=32A167454Numbers k such that k-1 | concat(k, k+1).at n=20A281233Numbers k that are a substring of k*(k-1).at n=35A316263