[[4]] is not prime (composite). Want proof? :)

Full prime factorization: [[2]] * [[2]]

Factor pairs:

[[4]] = [[2]] * [[2]]

Proper divisors: [[2]]

Primes up to 4: [[2]], [[3]].

[[4]] is not a centered hexagonal number.

The closest centered hexagonal numbers are [[1]] (index # [[1]]) and [[7]] (index # [[2]]).

First 20 centered hexagonal numbers: [[1]], [[7]], [[19]], [[37]], [[61]], [[91]], [[127]], [[169]], [[217]], [[271]], [[331]], [[397]], [[469]], [[547]], [[631]], [[721]], [[817]], [[919]], [[1027]], [[1141]].

[[hz/4]] is closest to [[C-2]] at [[4]] Hz (-38 cents).

Note class: [[C]], Octave: [[octave/-2]].

• [[square]]: 16

• [[square root]]: 2.0000

• [[cube]]: 64

• [[cube root]]: 1.5874

• [[natural log]] (ln): 1.3863

• [[base-10 log]] (log10): 0.6021

• [[base-2 log]] (log2): 2.0000