474768domain: NAppears in sequencesTheta series of direct sum of 4 copies of hexagonal lattice.at n=26A008655Triangle T(n,k) defined by Sum_{k=1..n} T(n,k)*u^k*x^n/n! = Product_{j>0} ( exp(j*x^j/(1 - x^j)) )^u.at n=41A338865