A276679 Number of divisors of the n-th hexagonal number.

1, 4, 4, 6, 6, 8, 4, 16, 6, 8, 8, 12, 6, 16, 8, 10, 8, 24, 4, 24, 8, 8, 12, 16, 9, 16, 8, 24, 8, 16, 4, 36, 16, 8, 16, 18, 4, 24, 16, 16, 10, 16, 8, 24, 12, 16, 8, 40, 6, 36, 8, 12, 16, 16, 8, 32, 8, 16, 12, 48, 6, 16, 24, 14, 16, 16, 8, 48, 8, 16, 8, 48, 8

Offset

1,2

Links

Colin Barker, Table of n, a(n) for n = 1..1000

Formula

a(n) = A000005(A000384(n)). - Omar E. Pol, Sep 13 2016

Example

a(6) = 8 because the 6th hexagonal number is 66, which has 8 divisors: 1,2,3,6,11,22,33,66.

Prog

(PARI)
pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number
vector(100, n, numdiv(pg(6, n)))

Crossrefs

Cf. A000005, A000384.

Number of divisors of m-gonal numbers (m = 3..10): A063440, A048691, A276678, this sequence, A276680, A276681, A276682, A276683.

Sequence in context: A196594 A190303 A175123 * A163638 A113523 A179278

Adjacent sequences: A276676 A276677 A276678 * A276680 A276681 A276682

Keyword

nonn

Author

Colin Barker, Sep 13 2016

Status

approved