“420 (number)”的意思、由来-开放百科全书

词条

420 (number)

释义

In mathematics
In other fields
References

420 (four hundred [and] twenty) is the natural number following 419 and preceding 421.

In mathematics

420 is:

the sum of four consecutive primes (101 + 103 + 107 + 109).
the sum of the first 20 positive even numbers.
a zero of the Mertens function^[1] and is sparsely totient.^[2]
a pronic number.^[3]
the smallest number divisible by the numbers 1 to 7, and as a consequence of that it is a Harshad number in every base from 2 to 10 except base 5.
a 141-gonal number.
a Harshad number.

In other fields

420 is a code-term that refers to the consumption of cannabis.

References

1. ^{{Cite web|url=https://oeis.org/A028442|title=Sloane's A028442 : Numbers n such that Mertens' function is zero|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-02}}
2. ^{{Cite web|url=https://oeis.org/A036913|title=Sloane's A036913 : Sparsely totient numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-02}}
3. ^{{Cite web|url=https://oeis.org/A002378|title=Sloane's A002378 : Oblong (or promic, pronic, or heteromecic) numbers|website=The On-Line Encyclopedia of Integer Sequences|publisher=OEIS Foundation|access-date=2016-06-02}}

1 : Integers

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