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 A109760 Composite n such that binomial(5*n,n) == 5^n (mod n). 2
 4, 365, 400, 685, 3200, 6400, 12550, 12800, 16525, 25600, 51200, 225125, 70463125, 271094125, 431434441 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS No other terms below 10^9. LINKS Max Alekseyev, PARI/GP scripts for various problems EXAMPLE 4 is a term because binomial(5*4, 4) = 4845, 5^4 = 625 and 4845 mod 4 = 625 mod 4 = 1. MATHEMATICA Do[If[ !PrimeQ[n], If[Mod[Binomial[5*n, n], n] == Mod[5^n, n], Print[n]]], {n, 1, 50000}] CROSSREFS Cf. A080469. Sequence in context: A215827 A051955 A177114 * A051181 A154682 A292195 Adjacent sequences:  A109757 A109758 A109759 * A109761 A109762 A109763 KEYWORD hard,more,nonn AUTHOR Ryan Propper, Aug 12 2005 EXTENSIONS a(12) from D. S. McNeil, Mar 15 2009 225125 from Max Alekseyev, Sep 13 2009 Three more terms from Max Alekseyev, Nov 06 2009 STATUS approved

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