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A338197
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a(n) is the number of distinct resistances that can be obtained by a network of exactly n equal resistors, but not by any network with fewer than n equal resistors.
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16
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1, 2, 4, 8, 20, 44, 114, 312, 894, 2639, 8005, 24362, 74918, 231123, 722388, 2276599, 7242497
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OFFSET
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1,2
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COMMENTS
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See A180414 and A337517 for more information and references.
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LINKS
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Table of n, a(n) for n=1..17.
Allan Gottlieb, Oct 3, 2003 addendum (Karnofsky).
Index to sequences related to resistances.
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FORMULA
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a(n) = A180414(n) - A180414(n-1).
a(n) = A051389(n) for n <= 5, a(n) > A051389(n) otherwise.
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EXAMPLE
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a(6) = 44 because the resistances 11/13 and 13/11 (in units of resistor value) are representable in addition to the A051389(6)=42 resistances that can be achieved by only serial and parallel configurations with exactly 6 resistors and not by a network with fewer than 6 resistors.
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CROSSREFS
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Cf. A051389, A180414, A337517, A338487.
Sequence in context: A051389 A078006 A288476 * A056952 A225585 A121703
Adjacent sequences: A338194 A338195 A338196 * A338198 A338200 A338201
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KEYWORD
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nonn,hard,more
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AUTHOR
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Hugo Pfoertner, Nov 03 2020
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EXTENSIONS
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a(15) corrected and a(16) added by Hugo Pfoertner, Dec 06 2020
a(17) from Hugo Pfoertner, Dec 09 2020
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STATUS
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approved
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