quiz
y.kohmoto
zbi74583 at boat.zero.ad.jp
Thu Dec 4 07:11:06 CET 2003
Hello, seqfans.
1/4-sigma or 1/4-aliquot sequence is defined as follows.
s(n)=1/4*sigma(a(n-1))
an example of periodic 1/4-sigma sequence : the period = 25
6943520030720 5386209454080 6389772480000 7665533854902 5756592291840
5657834203560 6382469882880 7938550287360 9055131471360 9256155068160
11798498589696 12316979136000 13937317954560 18314063179776
18071888486400 20136798781440 18850467643392 16492422758400
15699547839573 6635615891520 7400619883008 6494644316160 8009835724800
9317732578770 7847237806128
Please verify it.
a quiz :
How did I get this example?
1. A good method to calculate exists.
2. Exhaustive search.
3.Others.
comments :
1. A problem such that x=1/4*sigma(1/4*sigma....25 times....(x)....) is
too difficult to solve.
2. 14 digits is too many to do an exhaustive search.
3. What is it?
to Neil :
Managing any public project like OEIS is hard thing.
You receive a hundred sequences per day?
You add them on OEIS as a routine work.
Each sequence is "one of many sequences" for you, but an author of the
sequence never thinks so, it is the "only one sequence" for him.
If you slight them, they will claim you with many mails.
I did it several times.
But I think that if one really knows the purpose of OEIS then he will
not claim so much.
Explain it again to seqfans.
I suppose that a purpose of OEIS is "identification", but if so, why do
some "foolish" sequences such as "Kanji-sequence" exist?
It wastes 0.000001 sec for searching sequences.
If the purpose is "to be a encyclopedia" then people allows the
existence of a category " related with word".
But I feel that some of my sequences which were rejected fit to a
"encyclopedia", though they don't fit to the identification.
For example, above periodic 1/4-sigma sequence which was once rejected.
Yasutoshi
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