A048476 a(n) = T(4,n), array T given by A048472.
1, 6, 21, 61, 161, 401, 961, 2241, 5121, 11521, 25601, 56321, 122881, 266241, 573441, 1228801, 2621441, 5570561, 11796481, 24903681, 52428801, 110100481, 230686721, 482344961, 1006632961, 2097152001, 4362076161, 9059696641, 18790481921, 38923141121
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (5,-8,4).
Programs
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Magma
[5*n * 2^(n-1) + 1: n in [0..30]]; // Vincenzo Librandi, Sep 23 2011
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PARI
Vec((1+x-x^2)/((1-x)*(1-2*x)^2) + O(x^40)) \\ Colin Barker, Feb 18 2016
Formula
a(n) = 5*n * 2^(n-1) + 1.
a(n) = 5*a(n-1)-8*a(n-2)+4*a(n-3) for n>2. G.f.: (1+x-x^2) / ((1-x)*(1-2*x)^2). - Colin Barker, Feb 18 2016
Comments