This table is made for thermistor 3950 (can be found on ebay for cheap)
it's caracteristics are :

R25℃ ;100KΩ±1%

B Value(R25/50℃)：3990K 1%
Dissipation Factor(mW/℃)：1.1~1.6 In still Air
Thermal Time Constant(S)：10~17 In Still Air
Operating temperature range：  (-50~+260°C)
Dimension：  1.8mm Dia X4.1mm
Lead Length  ：30mm

This table was found on the following blogs:
http://cae2100.wordpress.com/2014/03/08/beta3950-thermistor-table-for-marlin/

and

http://microfabricator.com/articles/view/id/531ad7e59aad9d3131000000/beta-3950-thermistor-table-for-marlin
fix wrong temptable index
Merge pull request #877 from Nutz95/Marlin_v1

pull Request to Add beta 3950 1% thermistor table into marlin firmware