A047861 a(n) = T(4,n), array T given by A047858.
1, 6, 17, 41, 93, 205, 445, 957, 2045, 4349, 9213, 19453, 40957, 86013, 180221, 376829, 786429, 1638397, 3407869, 7077885, 14680061, 30408701, 62914557, 130023421, 268435453, 553648125, 1140850685, 2348810237, 4831838205, 9932111869, 20401094653, 41875931133
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..3000
- Index entries for linear recurrences with constant coefficients, signature (5,-8,4).
Programs
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Magma
[2^(n-1)*(n+8)-3: n in [0..30]]; // Vincenzo Librandi, Sep 28 2011
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PARI
Vec((1+x-5*x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 17 2016
Formula
Main diagonal of the array defined by T(0, j)=j+1 j>=0, T(i, 0)=i+1 i>=0, T(i, j)=T(i-1, j-1)+T(i-1, j)+ 3; a(n)=2^(n-1)*(n+8)-3. - Benoit Cloitre, Jun 17 2003
a(0)=1, a(1)=6, a(2)=17, a(n) = 5*a(n-1) -8*a(n-2) +4*a(n-3). - Vincenzo Librandi, Sep 28 2011
G.f.: (1+x-5*x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Feb 17 2016
Comments