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A108742 Row sums of a triangle related to the Jacobsthal polynomials. 2
1, 2, 3, 7, 12, 24, 45, 86, 164, 312, 595, 1133, 2159, 4113, 7836, 14929, 28442, 54187, 103235, 196680, 374708, 713881, 1360062, 2591144, 4936560, 9404967, 17918025, 34136815, 65036305, 123904968, 236059553, 449732674, 856815475, 1632375855 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Row sums of A108756.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,2,0,-1).

FORMULA

G.f.: (1 + x - x^2)/(1 - x - 2*x^2 + x^4).

a(n) = a(n - 1) + 2*a(n - 2) - a(n - 4) for n >= 4.

a(n) = Sum_{0 <= k <= n} binomial(floor((n + k + 1)/2) + k, floor((n + k)/2) - k).

MATHEMATICA

LinearRecurrence[{1, 2, 0, -1}, {1, 2, 3, 7}, 40] (* Harvey P. Dale, Feb 21 2016 *)

CROSSREFS

Sequence in context: A000630 A036538 A341407 * A018240 A090596 A355385

Adjacent sequences:  A108739 A108740 A108741 * A108743 A108744 A108745

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Jun 22 2005

STATUS

approved

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Last modified September 29 18:39 EDT 2022. Contains 357090 sequences. (Running on oeis4.)