56920domain: NAppears in sequencesNumber of solutions to +- 1 +- 2 +- 3 +- ... +- n = 0 or +- 1.at n=21A063867a(n) = floor((Pi^2/6)^n).at n=22A125892Number of compositions of n such that the first part is 1 and the second differences of the parts are in {-8,...,8}.at n=18A2395589*n analog to Keith numbers.at n=21A282764