A073094 - OEIS

%I #12 Jun 12 2018 02:42:24

%S 2,6,2,4,2,6,2,6,2,4,2,4,8,4,2,4,2,6,2,6,2,4,2,6,2,6,2,4,2,4,8,4,2,4,

%T 2,4,8,4,8,6,8,4,8,4,2,4,2,4,8,4,2,4,2,6,2,6,2,4,2,6,2,6,2,4,2,4,8,4,

%U 2,4,2,6,2,6,2,4,2,6,2,6,2,4,2,4,8,4,2,4,2,4,8,4,8,6,8,4,8,4,2,4,2,4,8,4,2

%N Final digit of C(2k,k) when not equal to zero.

%C Sequence contains 2,4,6,8, only.

%H Robert Israel, <a href="/A073094/b073094.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = C(2*A037453(n), A037453) reduced modulo 10.

%p f:= proc(n) local L,r;

%p   L:= convert(n,base,3);

%p   r:= 2 &^ numboccur(1,L) mod 5;

%p   r + 5*(r mod 2)

%p end proc:

%p map(f, [$1..200]); # _Robert Israel_, Jun 11 2018

%t Mod[#,10]&/@Table[Binomial[2n,n],{n,800}]/.(0->Nothing) (* _Harvey P. Dale_, Apr 14 2018 *)

%K easy,nonn,base

%O 1,1

%A _Benoit Cloitre_, Aug 18 2002