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

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, 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, 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

Offset

0,4

Comments

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.

Links

Table of n, a(n) for n=0..104.

Mathematica

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

Crossrefs

Cf. A039969, A113047, A113049.

Sequence in context: A252370 A045827 A070103 * A331671 A373925 A123758

Adjacent sequences: A113045 A113046 A113047 * A113049 A113050 A113051

Keyword

easy,nonn

Author

Paul Barry, Oct 11 2005

Status

approved