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 A098578 a(n) = Sum_{k=0..floor(n/4)} C(n-3*k,k+1). 7
 0, 1, 2, 3, 4, 6, 9, 13, 18, 25, 35, 49, 68, 94, 130, 180, 249, 344, 475, 656, 906, 1251, 1727, 2384, 3291, 4543, 6271, 8656, 11948, 16492, 22764, 31421, 43370, 59863, 82628, 114050, 157421, 217285, 299914, 413965, 571387, 788673, 1088588, 1502554 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Partial sums of A003269 (with leading zero). LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (2,-1,0,1,-1) FORMULA G.f.: x/((1-x)^2-x^4(1-x)) = x / ((x-1)*(x^4+x-1)). a(n) = 2*a(n-1) - a(n-2) + a(n-4) - a(n-5). a(n) = a(n-1) + a(n-4) + 1. MATHEMATICA a=b=c=0; Join[{d=0}, Table[e=a+d+1; a=b; b=c; c=d; d=e, {n, 100}]] (* Vladimir Joseph Stephan Orlovsky, Feb 26 2011*) CoefficientList[Series[x/((1-x)^2-x^4*(1-x)), {x, 0, 50}], x] (* or *) LinearRecurrence[{2, -1, 0, 1, -1}, {0, 1, 2, 3, 4}, 50] (* G. C. Greubel, Feb 03 2018 *) PROG (PARI) x='x+O('x^30); concat([0], Vec(x/((1-x)^2-x^4*(1-x)))) \\ G. C. Greubel, Feb 03 2018 (MAGMA) I:=[0, 1, 2, 3, 4]; [n le 5 select I[n] else 2*Self(n-1) - Self(n-2) + Self(n-4) - Self(n-5): n in [1..30]]; // G. C. Greubel, Feb 03 2018 CROSSREFS Cf. A077868. Sequence in context: A016028 A239551 A219282 * A303667 A050811 A076968 Adjacent sequences:  A098575 A098576 A098577 * A098579 A098580 A098581 KEYWORD easy,nonn AUTHOR Paul Barry, Sep 16 2004 STATUS approved

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Last modified April 5 00:43 EDT 2020. Contains 333238 sequences. (Running on oeis4.)