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A180012 a(n) = smallest k >= 1 such that k and k*n have the same digit sum. 2
1, 9, 9, 3, 9, 9, 3, 9, 9, 1, 99, 9, 9, 9, 9, 9, 9, 9, 6, 9, 54, 6, 9, 9, 6, 9, 9, 4, 9, 9, 33, 36, 99, 3, 9, 9, 3, 9, 9, 3, 27, 27, 24, 99, 9, 5, 9, 9, 9, 9, 63, 6, 27, 45, 2, 9, 9, 9, 9, 9, 33, 18, 18, 5, 18, 99, 3, 9, 9, 3, 72, 45, 7, 18, 18, 15, 99, 9, 9, 9, 63, 5, 27, 18, 6, 27, 36, 15, 9, 9, 11 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

D. W. Wilson, Table of n, a(n) for n=1..10000

EXAMPLE

For all 1 < k < 99, k and 11*k have distinct digit sum. 99 and 99*11 = 1089 have the same digit sum 18. Therefore a(11) = 99.

CROSSREFS

Sequence in context: A088398 A083949 A007471 * A172504 A172502 A118739

Adjacent sequences:  A180009 A180010 A180011 * A180013 A180014 A180015

KEYWORD

base,easy,nonn

AUTHOR

David W. Wilson, Aug 06 2010

STATUS

approved

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Last modified January 27 02:46 EST 2020. Contains 331291 sequences. (Running on oeis4.)