

A161751


Digital root of Abelian numbers (A051532).


0



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
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OFFSET

1,2


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]


LINKS

Table of n, a(n) for n=1..66.


EXAMPLE

161 is an Abelian number whose digital root is 8.


CROSSREFS

Cf. A051532
Sequence in context: A099088 A029447 A212317 * A105362 A115928 A117331
Adjacent sequences: A161748 A161749 A161750 * A161752 A161753 A161754


KEYWORD

nonn,base


AUTHOR

Parthasarathy Nambi, Jun 17 2009


STATUS

approved



