A073094 Final digit of C(2k,k) when not equal to zero.

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, 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, 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

Offset: 1

Author

Benoit Cloitre, Aug 18 2002

Keywords

• easy
• nonn
• base

Comments

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

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Programs

Maple

f:= proc(n) local L,r;
  L:= convert(n,base,3);
  r:= 2 &^ numboccur(1,L) mod 5;
  r + 5*(r mod 2)
end proc:
map(f, [$1..200]); # Robert Israel, Jun 11 2018

Mathematica

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

Formula

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