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Search: id:A144777
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| A144777 |
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Integers having decimal digital mean equal to zero. |
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+0
9
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| 18, 27, 36, 45, 54, 63, 72, 81, 90, 1089, 1098, 1179, 1188, 1197, 1269, 1278, 1287, 1296, 1359, 1368, 1377, 1386, 1395, 1449, 1458, 1467, 1476, 1485, 1494, 1539, 1548, 1557, 1566, 1575, 1584, 1593, 1629, 1638, 1647, 1656, 1665, 1674, 1683, 1692, 1719
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Define the digital mean of n in base b, dm(b, n), to be sigma(i in [1, d]: d_i * 2 - (b - 1)) / (2 * d), where d is the number of digits in the base b representation of n and d_i the individual digits.
a(n) is the subset of multiples of nine for which sigma(i in [1, d]: d_i * 2 - 9) = 0; that is, two times the sum of the digits is equal to nine times the number of digits.
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CROSSREFS
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Cf. A007953, A008591
Sequence in context: A151741 A090064 A082804 this_sequence A109911 A065751 A038632
Adjacent sequences: A144774 A144775 A144776 this_sequence A144778 A144779 A144780
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KEYWORD
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base,easy,nonn
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AUTHOR
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Reikku Kulon (reikku(AT)gmail.com), Sep 21 2008
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