194, 194, 191, 183, 168, ? Find the next number in the above series?

Here the series follows,

194

194 - (1x1 - 1) = 194

194 - (2x2 - 1) = 191

191 - (3x3 - 1) = 183

183 - (4x4 - 1) = 168

168 - (5x5 - 1) = 144