A113046 Diagonal sums of number triangle binomial(n, floor((n-k)/2)) mod 3.

1, 1, 3, 1, 1, 3, 5, 5, 6, 3, 3, 3, 3, 3, 3, 1, 1, 9, 11, 11, 12, 5, 5, 15, 16, 10, 12, 6, 6, 9, 9, 6, 6, 3, 3, 9, 9, 9, 9, 3, 3, 9, 9, 6, 6, 3, 3, 3, 3, 3, 3, 1, 1, 27, 29, 29, 30, 11, 11, 33, 34, 22, 24, 12, 12, 15, 15, 12, 12, 5, 5, 45, 46, 28, 30, 16, 16, 30, 32, 23, 24, 12, 12, 18, 18, 12

Offset: 0

Author

Paul Barry, Oct 11 2005

Keywords

• easy
• nonn

Comments

Diagonal sums of A113045.

Links

• Antti Karttunen, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A113045.

Programs

Maple

A113046:=n->add(binomial(n-k, floor((n-2*k)/2)) mod 3, k=0..floor(n/2)): seq(A113046(n), n=0..150); # Wesley Ivan Hurt, Jul 25 2017

PARI

A113046(n) = sum(k=0,n\2,binomial(n-k,((n-(2*k))\2))%3); \\ Antti Karttunen, Jul 24 2017

Formula

a(n) = Sum_{k=0..floor(n/2)} binomial(n-k, floor((n-2k)/2)) mod 3.