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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 (list; graph; refs; listen; history; text; internal format)
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 * A245820 A105362 A115928

Adjacent sequences:  A161748 A161749 A161750 * A161752 A161753 A161754

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Jun 17 2009

STATUS

approved

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Last modified August 22 01:35 EDT 2014. Contains 245921 sequences.