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 A113048 Binomial(4n,n)/(3n+1) mod 4. 1

%I

%S 1,1,0,2,0,1,0,0,0,0,0,2,0,2,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,

%T 0,0,0,0,0,0,0,0,0,2,0,2,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,

%U 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0

%N Binomial(4n,n)/(3n+1) mod 4.

%C It would appear that the behavior of this sequence is determined by values of the Jacobsthal numbers J(n)=A001045(n): a(n)=1 only if n=J(2k),k=0,1,...; a(n)=2 only if n=J(2k+3)+2J(2j), some k,j>=0, otherwise a(n)=0.

%t Table[Mod[Binomial[4n,n]/(3n+1),4],{n,0,120}] (* _Harvey P. Dale_, Mar 18 2018 *)

%Y Cf. A039969, A113047, A113049.

%K easy,nonn

%O 0,4

%A _Paul Barry_, Oct 11 2005

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Last modified June 19 06:47 EDT 2019. Contains 324218 sequences. (Running on oeis4.)