Table[FourierCoefficient[SquareWave[x/(2 Pi)], x, n], {n, 1, 10}]
Table[FourierCoefficient[SquareWave[x/(2 Pi)], x, n], {n, 1, 10}]; FindSequenceFunction[%, n]
Table[FourierCoefficient[SquareWave[x/(2 Pi)], x, n], {n, 1, 10}]; FindSequenceFunction[%, n]; Table[FourierCoefficient[SquareWave[x/(2 Pi)], x, n] - %, {n, 20}]