A109769 Composite n such that binomial(7*n, n) == 7^n (mod n).

18, 25, 133, 2107, 4676, 226037, 4477739, 827867201

Offset: 1

Author

Ryan Propper, Aug 13 2005

Keywords

• more
• nonn

Comments

No other terms below 10^9.

Examples

			18 is a term because binomial(7*18, 18) = 2797093093529137508875, 7^18 = 1628413597910449 and 2797093093529137508875 mod 18 = 1628413597910449 mod 18 = 1.
		

Links

• Max Alekseyev, PARI/GP scripts for various problems

Crossrefs

Cf. A080469.

Programs

Mathematica

Do[If[ !PrimeQ[n], If[Mod[Binomial[7*n, n], n] == Mod[7^n, n], Print[n]]], {n, 2, 20000}]

Extensions

226037 from Max Alekseyev, Sep 13 2009

Two more terms from Max Alekseyev, Nov 06 2009