A173489 Partial sums of A000140.

1, 2, 4, 10, 32, 133, 706, 4542, 33770, 284519, 2694100, 28292286, 324935676, 4052477864, 54679031852, 793359552994, 12294933375782, 202713354823112, 3547535843321377, 65667058958304601, 1280634899889213903

Offset: 1

Author

Jonathan Vos Post, Feb 19 2010

Keywords

• easy
• nonn

Crossrefs

Cf. A000140.

Programs

Mathematica

f[n_] := Max@ CoefficientList[ Expand@ Product[ Sum[x^i, {i, 0, j}], {j, n - 1}], x]; Accumulate@ Array[f, 21]

Formula

a(n) = Sum_{i=1..n} A000140(i).

a(n) ~ 6 * n^(n-1) / exp(n). - Vaclav Kotesovec, Oct 27 2016

Extensions

a(15) corrected by Georg Fischer, Aug 28 2020