82923domain: NAppears in sequencesSum of absolute values of real and imaginary parts of the coefficients in the expansion of 1 / (1 - x - 2*I*x^2), where I^2=-1.at n=19A218138Expansion of Sum_{k>=0} x^(k*(k+1)) / Product_{j=1..k} (1 - j*x^j).at n=35A306663