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A161751
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Digital root of Abelian numbers (A051532).
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0
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1, 2, 3, 4, 5, 7, 9, 2, 4, 6, 8, 1, 5, 7, 2, 4, 6, 8, 1, 5, 7, 9, 2, 4, 6, 8, 5, 7, 2, 4, 6, 8, 1, 5, 7, 2, 4, 6, 8, 1, 5, 7, 9, 2, 4, 8, 1, 5, 7, 2, 4, 6, 1, 5, 7, 2, 4, 6, 8, 1, 5, 7, 9, 4, 6, 8
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| It is interesting to observe that it is difficult to find 3 as the digital root.
This is because if a member of A051532 is congruent to 3 mod 9 all other prime power divisors of the number must be 2 mod 3. The first few indexes n with a(n) = 3 are 3, 99, 131, 164, 211, 261, 293, 327, 351, 424, 450, 482, 491, .... [From Charles R Greathouse IV, Feb 13 2011]
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EXAMPLE
| 161 is an Abelian number whose digital root is 8.
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CROSSREFS
| Cf. A051532
Sequence in context: A030290 A099088 A029447 * A105362 A115928 A117331
Adjacent sequences: A161748 A161749 A161750 * A161752 A161753 A161754
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KEYWORD
| nonn,base
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Jun 17 2009
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