A124789 - OEIS

A124789

Expansion of (1+x^2)/(1-x^4-x^5).

1, 0, 1, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 4, 4, 4, 5, 7, 8, 8, 9, 12, 15, 16, 17, 21, 27, 31, 33, 38, 48, 58, 64, 71, 86, 106, 122, 135, 157, 192, 228, 257, 292, 349, 420, 485, 549, 641, 769, 905, 1034, 1190, 1410, 1674, 1939, 2224, 2600, 3084, 3613

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OFFSET

0,10

COMMENTS

Diagonal sums of A124788.

LINKS

Table of n, a(n) for n=0..59.

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

FORMULA

a(n) = Sum_{k=0..floor(n/2)} C(floor(k/2),n-2*k).

a(n) = A017827(n)+A017827(n-2). - R. J. Mathar, May 09 2013

a(n) = A103372(n-3) for n >= 4. - Georg Fischer, Nov 03 2018

a(n) = (-1)^n*A124746(n). - R. J. Mathar, Jun 30 2020

MATHEMATICA

CoefficientList[Series[(1+x^2)/(1-x^4-x^5), {x, 0, 60}], x] (* or *) LinearRecurrence[ {0, 0, 0, 1, 1}, {1, 0, 1, 0, 1}, 60] (* Harvey P. Dale, Aug 20 2013 *)

CROSSREFS

Cf. A017827, A103372.

Sequence in context: A363337 A304633 A124746 * A103372 A029082 A035450

Adjacent sequences: A124786 A124787 A124788 * A124790 A124791 A124792

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Nov 07 2006

STATUS

approved