228 (number)

228 (two hundred [and] twenty-eight) is the natural number following 227 and preceding 229.

In mathematics

← 227 228 229 →
Cardinaltwo hundred twenty-eight
Ordinal228th
(two hundred twenty-eighth)
Factorization22 × 3 × 19
Primeno
Greek numeralΣΚΗ´
Roman numeralCCXXVIII
Binary111001002
Ternary221103
Senary10206
Octal3448
Duodecimal17012
HexadecimalE416

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

  1. ^ Sloane, N. J. A. (ed.). "Sequence A033950 (Refactorable numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  2. ^ Sloane, N. J. A. (ed.). "Sequence A005153 (Practical numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.
  3. ^ 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.
  4. ^ 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.
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