maybe 12 series LED's fed with 10 74HC4017 outputs
and 10 NPN transistor switch's ?

--+--|--+--|--+--|--+--|--+--|--+--
| |
1of10 | |
4017 | /
OUT------+------------------|
25mA \
v
|
_____
___
_

Jim Davis wrote:

A 74HC4017 decade counter has 10 outputs ,
one output 25mA high at a time ,
with max V+ of 6 VDC .
Thus each 74HC4017 output can light 3 series LED's .

Chris W wrote:

I want to flash LED's in an interesting sequence
... ascii art to show the sequence. O = on, X = off.

OOOXXXXXXX
XOOOXXXXXX
XXOOOXXXXX
XXXOOOXXXX
XXXXOOOXXX
XXXXXOOOXX
XXXXXXOOOX
XXXXXXXOOO

Then repeat or maybe reverse it and then repeat. This shows 10 LEDs,
but I may be using 15 or 20.