228 (two hundred [and] twenty-eight) is the natural number following 227 and preceding 229.
In mathematics
228 is a refactorable number[1] and a practical number.[2] There are 228 matchings in a ladder graph with five rungs.[3] 228 is the smallest even number n such that the numerator of the nth Bernoulli number is divisible by a nontrivial square number that is relatively prime to n.[4]
The binary form of 228 contains all the two digit binary numbers in sequence from highest to lowest (11 10 01 00).
References
- ^ Sloane, N. J. A. (ed.). "Sequence A033950 (Refactorable numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A005153 (Practical numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A030186 (a(n) = 3a(n-1) + a(n-2) - a(n-3))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
- ^ Sloane, N. J. A. (ed.). "Sequence A090943 (Even numbers n such that N(n) is divisible by a nontrivial square, m^2, say and GCD(n,m)=1, where N(n) is the numerator of the Bernoulli number B(n))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.