64636domain: NAppears in sequencesNumber of discordant permutations.at n=23A000561One of the two successive approximations up to 5^n for the 5-adic integer sqrt(-4). These are the 1 mod 5 numbers, except for n = 0.at n=7A268922Number of same-sized pairs of subsets of set of n numbers that might have the same sum.at n=12A304011