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A109760
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Composite n such that binomial(5*n,n) == 5^n (mod n).
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1
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4, 365, 400, 685, 3200, 6400, 12550, 12800, 16525, 25600, 51200, 225125, 70463125, 271094125, 431434441
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| No other terms below 10^9.
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LINKS
| Max Alekseyev, PARI/GP scripts for various problems
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EXAMPLE
| 4 is a term because binomial(5*4, 4) = 4845, 5^4 = 625 and 4845 mod 4 = 625 mod 4 = 1.
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MATHEMATICA
| Do[If[ !PrimeQ[n], If[Mod[Binomial[5*n, n], n] == Mod[5^n, n], Print[n]]], {n, 1, 50000}]
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CROSSREFS
| Cf. A080469.
Sequence in context: A203034 A051955 A177114 * A051181 A154682 A154569
Adjacent sequences: A109757 A109758 A109759 * A109761 A109762 A109763
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KEYWORD
| hard,more,nonn
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AUTHOR
| Ryan Propper (rpropper(AT)stanford.edu), Aug 12 2005
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EXTENSIONS
| a(12) from D. S. McNeil (d.mcneil(AT)qmul.ac.uk), Mar 15 2009
225125 from Max Alekseyev (maxale(AT)gmail.com), Sep 13 2009
Three more terms from Max Alekseyev (maxale(AT)gmail.com), Nov 06 2009
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