[seqfan] Re: A000959: Lucky numbers

hv at crypt.org hv at crypt.org
Fri Oct 29 11:28:32 CEST 2010


Earlier I wrote:
:The file <http://crypt.org/hv/maths/lucky_1e8.bz2> lists the lucky numbers
:up to 1e8. The file has 5,286,238 entries; filesize is 46,884,917 bytes,
:compressed to 16,490,206 bytes.

The file <http://crypt.org/hv/maths/lucky_1e9.bz2> lists the lucky numbers
up to 1e9. The file has 46,697,909 entries; filesize is 461,001,627 bytes,
compressed to 146,896,025 bytes.

:I verified the results up to 5e6 with code provided by David Wilson that
:used a completely different algorithm, so I have high confidence in these
:results. My code is at <http://crypt.org/hv/maths/cgen_lucky.c> (2,762
:bytes).
:
:The program has now reached 3e8 after 17 CPU hours; I'll let it run until
:1e9 or until I need the processor back, and make the full results available
:as a separate file. (I estimate it'll take >6 CPU days to reach 1e9: the
:slowdown for large n is rather worse than I'd guessed based on small n.)

In the event it took 180 CPU hours to reach 1e9.

Hugo




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