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A117910 Expansion of (1+x+x^2+x^4)/((1-x^3)(1-x^6)). 1
1, 1, 1, 1, 2, 1, 2, 3, 2, 2, 4, 2, 3, 5, 3, 3, 6, 3, 4, 7, 4, 4, 8, 4, 5, 9, 5, 5, 10, 5, 6, 11, 6, 6, 12, 6, 7, 13, 7, 7, 14, 7, 8, 15, 8, 8, 16, 8, 9, 17, 9, 9, 18, 9, 10, 19, 10, 10, 20, 10, 11, 21, 11, 11, 22, 11, 12, 23, 12, 12, 24, 12, 13, 25, 13, 13, 26, 13, 14, 27, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

Diagonal sums of A117908. Appears to be a permutation of floor((n+5)/5).

LINKS

Table of n, a(n) for n=0..80.

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

FORMULA

a(n)=a(n-3)+a(n-6)-a(n-9); a(n)=sum{k=0..floor(n/2),0^abs(L(C(n-k,2)/3)-2*L(C(k,2)/3))} where L(j/p) is the Legendre symbol of j and p.

a(0)=1, a(1)=1, a(2)=1, a(3)=1, a(4)=2, a(5)=1, a(6)=2, a(7)=3, a(8)=2, a(n)=a(n-3)+ a(n-6)- a(n-9). - Harvey P. Dale, Apr 10 2014

MATHEMATICA

CoefficientList[Series[(1+x+x^2+x^4)/((1-x^3)(1-x^6)), {x, 0, 100}], x] (* or *) LinearRecurrence[{0, 0, 1, 0, 0, 1, 0, 0, -1}, {1, 1, 1, 1, 2, 1, 2, 3, 2}, 100] (* Harvey P. Dale, Apr 10 2014 *)

CROSSREFS

Sequence in context: A174961 A104889 A290979 * A275435 A029267 A111725

Adjacent sequences:  A117907 A117908 A117909 * A117911 A117912 A117913

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Apr 01 2006

STATUS

approved

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Last modified May 24 01:29 EDT 2019. Contains 323528 sequences. (Running on oeis4.)