A124751 Expansion of (1+x^2+x^4)/(1-x^6+x^7).

1, 0, 1, 0, 1, 0, 1, -1, 1, -1, 1, -1, 1, -2, 2, -2, 2, -2, 2, -3, 4, -4, 4, -4, 4, -5, 7, -8, 8, -8, 8, -9, 12, -15, 16, -16, 16, -17, 21, -27, 31, -32, 32, -33, 38, -48, 58, -63, 64, -65, 71, -86, 106, -121, 127, -129, 136, -157, 192, -227, 248

Offset

0,14

Comments

Diagonal sums of number triangle A124749.

Links

Table of n, a(n) for n=0..60.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,1,-1).

Formula

a(n)=sum{k=0..floor(n/2), C(floor(k/3),n-2k)*(-1)^n}

Mathematica

CoefficientList[Series[(1+x^2+x^4)/(1-x^6+x^7), {x, 0, 100}], x] (* or *) LinearRecurrence[{0, 0, 0, 0, 0, 1, -1}, {1, 0, 1, 0, 1, 0, 1}, 100] (* Harvey P. Dale, Mar 10 2017 *)

Crossrefs

Sequence in context: A317245 A332277 A109701 * A103374 A208251 A241087

Adjacent sequences: A124748 A124749 A124750 * A124752 A124753 A124754

Keyword

easy,sign

Author

Paul Barry, Nov 06 2006

Status

approved