Noob question: blinking leds with pn2222A and 9v battery
You need to understand the power capacity of various battery technology in Ah, Wh and how this degrades due to ESR self-heating and when you exceed rated current.

Using a 9V battery rated for 550mAh in 20 hours when drops well below 8V.

Ideally under low current, a 9V battery can provide 550mAh * 9V  &lt;5Wh or 27.5mA for 20 h.

You have 39x 2V LEDs @ 20mA = 1.56 Amps or more than  50x times ~~ its 20h rated capacity. Then by dropping 7V in resistors you are wasting 7/9= 77% of the battery power.

Rules to remember


Choose a primary battery with a 20h capacity 
choose a battery to match your string voltage at dim voltage when the battery is discharged  ( e.g. 1.75V dim 2.1V +/-25% bright per YEL 5mm LED )
Choose a series R and Pd to current limit when the battery is new. I=ΔV/R current limit
Most LEDs have 25% tolerance on Vf at I rated.  


Better suppliers are 5% from the same batch or bin e.g. 2.05+/-0.1V 
or even better 2.0~2.1V for Red , Yellow
This is inherently due to MFG tolerances on bulk resistance of the diode and sorting.

e.g. 20mA @ 2.05V ~ 41 mW with an Rs of ~12 (+/-25%) Ohms


so @ 10mA the voltage drops 120mV +/-25% from 2.05 to 1.93V per LED * 10 mA ~ 19mW 
then drops to maybe 1.75V at for a dim LED. Consult with Datasheet for nominal VI curve or similar part



So your battery choice is N.G.

More Rules to Remember


Your transistor switch must handle much more current than you plan to use to allow cool operation as they are rated with infinite heatsinks or pulse current @ 25'C
Current switch choice must have low Vce(sat) at Imax or low voltage drop 
2N2222 cannot handle 1.5A.  
If you cannot tolerate a 0.5 to 1V drop , use a low ROn FET that can.








simulate this circuit &ndash; Schematic created using CircuitLab