gistfile1.rebol

REBOL []
print dp [
  m: make map! 2 * n: to-integer first system/options/args
  repeat i n [m/(i): i]
]

gistfile2.txt

13000000 timer: 0:00:14.147284 series-bytes: 1100436112
14000000 timer: 0:00:15.603917 series-bytes: 1164436112
15000000 timer: 0:00:15.943811 series-bytes: 1228436112
16000000 timer: 0:00:17.226752 series-bytes: 1292436112
17000000 timer: 0:00:32.279338 series-bytes: 1624871432
18000000 timer: 0:00:40.582115 series-bytes: 1688871432
19000000 timer: 0:00:56.489113 series-bytes: 1752871432
20000000 timer: 0:01:26.615458 series-bytes: 1816871432
21000000 timer: 0:03:34.544310 series-bytes: 1880871432
22000000 timer: 0:11:16.081855 series-bytes: 1944871432