38797312domain: NAppears in sequences4th binomial transform of (1,3,0,0,0,0,0,.....).at n=11A081039Expansion of g.f. (1 - x)^2*(1 + x) / (1 - 2*x)^2.at n=22A106472a(0)=8, a(n) = 2*a(n-1) + 2^(n-1) for n > 0.at n=21A159696a(n) is the first number == 1 (mod n) that is the product of n primes, counted by multiplicity.at n=20A368217