180 (number) two square numbers: 12 + 6. It can be expressed as either the sum of six consecutive prime numbers: 19 + 23 + 29 + 31 + 37 + 41, or the sum of eight consecutive prime numbers: 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37. 180 is an Ulam number, which can be expressed as a sum of earlier terms in the Ulam sequence only as 177 + 3. 180 is a 61-gonal number. Half a circle has 180 degrees. Summing Euler's totient function φ("x") over the first + 24 integers gives
Prime number examples of prime-generating formulas come from Mills' theorem and a theorem of Wright. These assert that there are real constants formula_51 and formula_52 such that are prime for any natural number formula_1 in the first formula, and any number of exponents in the second formula. Here formula_55 represents the floor function, the largest integer less than or equal to the number in question. However, these are not useful for generating primes, as the primes must be generated first in order to compute the values of formula_56 or formula_52. Many conjectures revolving about primes have been posed. Often having an elementary