A337990 Number of compositions (ordered partitions) of n^n into powers of n.

1, 1, 6, 26426, 773527571233557154337704151068262296

Offset: 0

Author

Ilya Gutkovskiy, Oct 06 2020

Keywords

• nonn

Comments

The next term is too large to include.

Examples

			a(2) = 6 because 2^2 = 4 and we have [4], [2, 2], [2, 1, 1] (3 permutations), [1, 1, 1, 1] and 1 + 1 + 3 + 1 = 6.
		

Links

• Index entries for sequences related to compositions

Crossrefs

Cf. A145514, A248377.

Programs

Mathematica

Join[{1, 1}, Table[SeriesCoefficient[1/(1 - Sum[x^(n^k), {k, 0, n}]), {x, 0, n^n}], {n, 2, 4}]]

Formula

a(n) = [x^(n^n)] 1 / (1 - Sum_{k>=0} x^(n^k)), for n > 1.