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Search: id:A101620
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| A101620 |
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Decimal encoding of digraph topologies. |
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+0
1
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| 1, 3, 9, 11, 13, 15, 129, 131, 133, 137, 139, 141, 143, 145, 153, 161, 163, 165, 171, 175, 177, 179, 187, 193, 195, 197, 205, 207, 209, 213, 221, 241, 243, 245, 255
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The sequence encodes labeled digraph topologies as described by and counted in A000798.
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EXAMPLE
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Let a = 2, b = 4, c = 16, d = 256, ...
a(19) = 171 because we can map { }, a, ab, ac, abc to 1 + 2 + 8 + 32 + 128
Viewed as an array the table begins
1
3
9 11 13 15
129 131 133 137 139 141 143 145 153 161 163 165 171 175 177 ...
with respectively 1 1 4 29 355 ... (A000798) entries on each row.
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CROSSREFS
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Cf. A000798, A001035, A001930, A074486.
Adjacent sequences: A101617 A101618 A101619 this_sequence A101621 A101622 A101623
Sequence in context: A074261 A059868 A101735 this_sequence A116444 A065136 A075720
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KEYWORD
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more,nonn,tabf
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AUTHOR
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Alford Arnold (Alford1940(AT)aol.com), Dec 10 2004
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