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 A190139 a(n) = 2*a(n-1) + a(n-2) + a(n-3) + a(n-4), a(-2)=0, a(-1)=0, a(0)=1, a(1)=1. 1
 1, 1, 3, 8, 21, 54, 140, 363, 941, 2439, 6322, 16387, 42476, 110100, 285385, 739733, 1917427, 4970072, 12882689, 33392610, 86555408, 224356187, 581543081, 1507390367, 3907235410, 10127760455, 26251689768, 68045765768, 176378217169, 457181650329, 1185038973363 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Number of compositions of n where there is one sort of part 1, two sorts of part 2, three sorts of part 3, and four sorts of every other part. - Joerg Arndt, Mar 15 2014 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 (terms 0..200 from Vincenzo Librandi) Yüksel Soykan, A Study of Generalized Fourth-Order Pell Sequences, Journal of Scientific Research & Reports (2019) Vol. 25, No. 1, 1-18, Article No. JSRR.52074. Index entries for linear recurrences with constant coefficients, signature (2,1,1,1) FORMULA G.f.: (1-x)/(1-2*x-x^2-x^3-x^4). a(n) = Sum_{k=1..n} (Sum_{t=k..n} (Sum_{j=0..k} C(k,j) * Sum_{i=j..t-k+j} C(j,i-j)*C(k-j,t-3*(k-j)-i)*C(-t+n+k-1,k-1))), n>0, a(0)=1. a(n) = A103142(n) - A103142(n-1). - R. J. Mathar, Sep 17 2011 MATHEMATICA RecurrenceTable[{a[n] == 2 a[n - 1] + a[n - 2] + a[n - 3] + a[n - 4], a[-2] == a[-1] == 0, a[0] == a[1] == 1}, a, {n, 0, 30}] (* Michael De Vlieger, Oct 28 2015 *) LinearRecurrence[{2, 1, 1, 1}, {1, 1, 3, 8}, 31] (* Michael De Vlieger, Oct 28 2015 *) PROG (Maxima) a(n):=sum(sum((sum(binomial(k, j)*sum(binomial(j, i-j)*binomial(k-j, t-3*(k-j)-i), i, j, t-k+j), j, 0, k))*binomial(-t+n+k-1, k-1), t, k, n), k, 1, n); (MAGMA) I:=[1, 1, 3, 8]; [n le 4 select I[n] else 2*Self(n-1)+Self(n-2)+Self(n-3)+Self(n-4): n in [1..40]]; // Vincenzo Librandi, Sep 20 2011 (PARI) x='x+O('x^30); Vec((1-x)/(1-2*x-x^2-x^3-x^4)) \\ G. C. Greubel, Dec 29 2017 CROSSREFS Sequence in context: A077849 A135473 A242452 * A005580 A292619 A231222 Adjacent sequences:  A190136 A190137 A190138 * A190140 A190141 A190142 KEYWORD nonn AUTHOR Vladimir Kruchinin, May 05 2011 STATUS approved

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Last modified May 31 22:11 EDT 2020. Contains 334756 sequences. (Running on oeis4.)