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Search: id:A155504
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| A155504 |
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Numbers of the form (3h+1)*3^(k+1) listed in increasing order. |
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+0
1
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| 3, 9, 12, 21, 27, 30, 36, 39, 48, 57, 63, 66, 75, 81, 84, 90, 93, 102, 108, 111, 117, 120, 129, 138, 144, 147, 156, 165, 171, 174, 183, 189, 192, 198, 201, 210, 219, 225, 228, 237, 243, 246, 252, 255, 264, 270, 273, 279, 282, 291, 300, 306
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This sequence, call it S and the sequence A016777, call it U, can be defined by mutual induction from the following clauses:
a) 1 belongs to U;
b) if n belongs to S and m belongs to U then n+m belongs to U;
c) if m belongs to U then 3m belongs to S;
d) if n belongs to S then 3n belongs to S.
A computer-checked proof of this fact is available in the HELM digital library.
This sequence appears to contain the numbers whose allegorical signification is connected to the concept of balance according to the Hebrew-Christian-Islamic mystic tradition.
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REFERENCES
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F. C. Endres and A. Schimmel, Das Mysterium der Zahl, Eugen Diederichs Verlag, Cologne, 1984 (Italian edition). 1
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CROSSREFS
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Cf. A016777.
Sequence in context: A006499 A140979 A096726 this_sequence A022379 A081601 A137344
Adjacent sequences: A155501 A155502 A155503 this_sequence A155505 A155506 A155507
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KEYWORD
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nonn
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AUTHOR
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Ferruccio Guidi (fguidi(AT)cs.unibo.it), Jan 23 2009
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