44060domain: NAppears in sequencesAlmost-convex polygons of perimeter 2n on square lattice.at n=3A007221Difference between F(n) = 2^(2^n)+1 and nextprime(F(n)) where F(n) is the n-th Fermat Number.at n=16A097521a(1) = 1; a(n) = 1 + a(n-1) + Sum_{k=2..n} a(floor(n/k)).at n=48A351621