A271320 Number of prime factors, with multiplicity, of the n-th n-gonal number (A060354).

1, 2, 4, 2, 3, 5, 5, 3, 3, 3, 7, 2, 3, 5, 6, 3, 4, 4, 6, 3, 3, 5, 6, 3, 4, 5, 9, 2, 5, 4, 7, 4, 4, 4, 7, 2, 4, 9, 7, 3, 4, 3, 7, 4, 3, 5, 7, 3, 5, 4, 7, 2, 6, 6, 6, 4, 3, 3, 9, 4, 3, 7, 8, 3, 4, 4, 7, 4, 4, 6, 8, 2, 4, 6, 7, 3, 4, 4, 8, 6, 4, 4, 8, 4, 3, 6

Offset

2,2

Links

Colin Barker, Table of n, a(n) for n = 2..1000

Formula

a(n) = A001222(A060354(n)).

Example

a(7) = 5 because A060354(7) = 112 = 2^4 * 7^1.

Prog

(PARI)
pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number
a(n) = bigomega(pg(n, n))
vector(100, n, n++; a(n))

Crossrefs

Cf. A001222, A060354, A271319, A271321, A271322.

Sequence in context: A082864 A134447 A093056 * A354739 A348486 A331279

Adjacent sequences: A271317 A271318 A271319 * A271321 A271322 A271323

Keyword

nonn

Author

Colin Barker, Apr 04 2016

Status

approved