# Number of subsets of {1,2,3,...,n} that sum to 0 mod 17

Creighton Dement crowdog at crowdog.de
Sat Jul 23 13:53:59 CEST 2005

```Dear Seqfans, hi Antti,

With the exception of the 17th and 33rd terms of
http://www.research.att.com/projects/OEIS?Anum=A068038
I get a floretion sequence that matches numbers from this sequence:

1jbasekzapsumseq[(- .5'j + .5'k - .5j' + .5k' - 'ii' - .5'ij' - .5'ik' -
.5'ji' - .5'ki')*(+ .5'i + .5'j + .5i' + .5j')]:
0, 0, -2, -2, -2, -2, 30, 30, 30, 30, -482, -482, -482, -482, 7710,
7710, 7710, 7710, -123362, -123362, -123362, -123362, 1973790, 1973790,
1973790, 1973790, -31580642, -31580642, -31580642, -31580642, 505290270

Notice that  A068038(9) = 30,  A068038(9+4) = 482,
A068038(9+8) = 7712, A068038(9+12) = 123362,
A068038(9+16) = 1973790, A068038(9+20) = 31580642,
A068038(9+24) = 505290272

Note: above numbers converted from base 10 to base 4 :
(30)_10 = (132)_4
(482)_10 = (13202)_4
(7710)_10 = (1320132)_4; (7712)_10  = (1320200)_4
(123362)_10 = (132013202)_4
etc.

To be on the safe side, I would suggest that the 17th term of A068038 is
recalculated.

Sincerely,
Creighton

```