183 (number)

183 (one hundred [and] eighty-three) is the natural number following 182 and preceding 184.

In mathematics
183 is a perfect totient number, a number that is equal to the sum of its iterated totients.

Because $$183 = 13^2 + 13 + 1$$, it is the number of points in a projective plane over the finite field $$\mathbb{Z}_{13}$$. 183 is the fourth element of a divisibility sequence $$1,3,13,183,\dots$$ in which the $$n$$th number $$a_n$$ can be computed as $$a_n=a_{n-1}^2+a_{n-1}+1=\bigl\lfloor x^{2^n}\bigr\rfloor,$$ for a transcendental number $$x\approx 1.38509$$. This sequence counts the number of trees of height $$\le n$$ in which each node can have at most two children.

There are 183 different semiorders on four labeled elements.