A098527 - OEIS

A098527

Expansion (1+x^3)/(1-x-x^7).

1, 1, 1, 2, 2, 2, 2, 3, 4, 5, 7, 9, 11, 13, 16, 20, 25, 32, 41, 52, 65, 81, 101, 126, 158, 199, 251, 316, 397, 498, 624, 782, 981, 1232, 1548, 1945, 2443, 3067, 3849, 4830, 6062, 7610, 9555, 11998, 15065, 18914, 23744, 29806, 37416, 46971, 58969, 74034, 92948

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OFFSET

0,4

COMMENTS

The expansion of (1+kx^2)/(1-x-k^2*x^7) satisfies the recurrence a(n)=a(n-1)+k^2*a(n-7),a(0)=1,a(1)=1,a(2)=1,a(3)=k+1,a(4)=k+1, a(5)=k+1,a(6)=k+1 with a(n)=sum{k=0..floor(n/3), binomial(n-3k,floor(k/2))r^k}.

LINKS

Table of n, a(n) for n=0..52.

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

FORMULA

a(n)=a(n-1)+a(n-7); a(n)=sum{k=0..floor(n/3), binomial(n-3k, floor(k/2))}.

MATHEMATICA

CoefficientList[Series[(1+x^3)/(1-x-x^7), {x, 0, 60}], x] (* or *) LinearRecurrence[ {1, 0, 0, 0, 0, 0, 1}, {1, 1, 1, 2, 2, 2, 2}, 60] (* Harvey P. Dale, Oct 07 2018 *)

CROSSREFS

Cf. A097333, A098523.

Sequence in context: A241901 A238213 A193942 * A035635 A114869 A316899

Adjacent sequences: A098524 A098525 A098526 * A098528 A098529 A098530

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Sep 12 2004

STATUS

approved