# [seqfan] Re: formula for A062204

Max Alekseyev maxale at gmail.com
Fri Mar 13 04:36:28 CET 2009

```In the previous message, I've mistakenly exchanged the length of
strings y with the number strings n (following notations in A062204).
Thus, the correct formula is:
B(y,n) = sum(k=y,n*y, sum(t=0,k, (-1)^t * binomial(k,t) * binomial(k-t,y)^n ))

B(y,2) for y=0,1,2,... gives A001850.

The sequences A062208, A062205, and A062204 correspond to y=3, y=4,
and y=7 respectively (for n=0,1,2,...).
The correct terms of these sequences are:

A062208 (y=3) for n=0..10:
0, 1, 63, 16081, 10681263, 14638956721, 35941784497263,
143743469278461361, 874531783382503604463, 7687300579969605991710001,
93777824804632275267836362863

A062205 (y=4) for n=0..10:
0, 1, 321, 699121, 5552351121, 117029959485121, 5402040231378569121,
480086443888959812703121, 74896283763383392805211587121,
19133358944433370977791260580721121,
7581761490297442738124283591348762605121

A062204 (y=7) for n=0..10:
0, 1, 48639, 75494983297, 1177359342144641535,
103746115308050354021387521, 36585008462723983824862891403150079,
41020870889694863957061607086939138327565057,
124069835911824710311393852646151897334844371419287295,
894709632166224106718347951886305028154659386016685862593012481,
13974111175679289927570338050856039748598663087886090141949924306299672319

Regards,
Max

```