A371212 Number of ordered factorizations of n into factors > 4.

1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1, 3, 2, 1, 1, 1, 3, 1, 3, 1, 1, 3, 1, 1, 3, 2, 3, 1, 1, 1, 3, 3, 3, 1, 1, 1, 5, 1, 1, 3, 2, 3, 3, 1, 1, 1, 5, 1, 5, 1, 1, 3, 1, 3, 3, 1, 5, 2, 1, 1, 5, 3, 1, 1, 3, 1, 7, 3, 1

Offset

1,25

Links

Table of n, a(n) for n=1..92.

Formula

a(1) = 1; a(n) = Sum_{d|n, n/d > 4} a(d).

Example

a(30) = 3: 30 = 5*6 = 6*5.

Mathematica

a[n_] := a[n] = If[n == 1, n, Sum[If[n/d > 4, a[d], 0], {d, Divisors[n]}]]; Table[a[n], {n, 1, 92}]

Crossrefs

Cf. A002033, A017899, A074206, A185325, A371209, A371211, A371213.

Sequence in context: A137773 A175010 A107454 * A250261 A063669 A306489

Adjacent sequences: A371209 A371210 A371211 * A371213 A371214 A371215

Keyword

nonn

Author

Ilya Gutkovskiy, Mar 15 2024

Status

approved