

A109769


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


2




OFFSET

1,1


COMMENTS

No other terms below 10^9.


LINKS

Table of n, a(n) for n=1..8.
Max Alekseyev, PARI/GP scripts for various problems


EXAMPLE

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


MATHEMATICA

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


CROSSREFS

Cf. A080469.
Sequence in context: A003300 A245022 A248111 * A229967 A212049 A212052
Adjacent sequences: A109766 A109767 A109768 * A109770 A109771 A109772


KEYWORD

more,nonn


AUTHOR

Ryan Propper, Aug 13 2005


EXTENSIONS

226037 from Max Alekseyev, Sep 13 2009
Two more terms from Max Alekseyev, Nov 06 2009


STATUS

approved



