A389242 Expansion of e.g.f. exp(x^5/120 * cosh(x)).

1, 0, 0, 0, 0, 1, 0, 21, 0, 126, 126, 462, 16632, 1287, 1009008, 129129, 32288256, 51465596, 705729024, 10266163524, 12407843448, 1252470551661, 618576390432, 101481644822173, 209811307128192, 6091619706481386, 61249808357337600, 300421930089201570, 12641972599683947520, 19716582552980551875

Offset

0,8

Comments

Number of ways to choose five elements from each block of the partitions of an n-set into odd blocks (see Example).

Links

Table of n, a(n) for n=0..29.

Example

a(12) = 16632 since the number of ways to choose five elements from each block of the partitions of a 12-set into odd blocks are:
  Sample partition {1,2,3,4,5} {6,7,8,9,10,11,12}: 792 such partitions, 16632 ways.
  Note that for other partitions into odd blocks such as {1,2,3,4,5} {6,7,8,9,10} {11} {12} it is not possible to choose five elements from each block.

Crossrefs

Cf. A003724, A003727, A389149.

Sequence in context: A324685 A224114 A110454 * A265156 A040445 A040446

Adjacent sequences: A389239 A389240 A389241 * A389243 A389244 A389245

Keyword

nonn

Author

Enrique Navarrete, Sep 26 2025

Status

approved