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Search: id:A056188
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| A056188 |
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Sum of binomial[n,k] as k runs over RRS[n], the reduced residue system of n. |
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+0
3
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| 1, 2, 6, 8, 30, 12, 126, 128, 342, 260, 2046, 1608, 8190, 4760, 15840, 32768, 131070, 80820, 524286, 493280, 1165542, 1391720, 8388606, 5769552, 26910650, 23153832, 89478486, 131849648, 536870910, 352845960, 2147483646, 2147483648
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)= Sum{binomial[n, k]; GCD[n, k]=1, 0<k<n}
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EXAMPLE
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n=prime, a(n)=2^n-2 because all k<=n except 0 and n are used; n=10, RRS[10]={1,3,7,9}, the corresponding coefficients are {10,120,120,10}, so the sum a(10)=260.
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MATHEMATICA
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f[n_] := Plus @@ Binomial[n, Select[ Range[n], GCD[n, # ] == 1 &]]; Table[ f[n], {n, 33}] (from Robert G. Wilson v Nov 04 2004)
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CROSSREFS
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Cf. A056045, A056189.
Adjacent sequences: A056185 A056186 A056187 this_sequence A056189 A056190 A056191
Sequence in context: A116083 A115506 A057852 this_sequence A020696 A132269 A053287
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Aug 02 2000
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