A087946 Expansion of (1-3x+x^2)/((1-2x)(1-4x+x^2)).
1, 3, 10, 35, 126, 461, 1702, 6315, 23494, 87533, 326382, 1217483, 4542526, 16950573, 63255670, 236063915, 880983606, 3287837741, 12270301822, 45793238475, 170902389934, 637815796973, 2380359749382, 8883621103403
Offset: 0
Links
- Index entries for linear recurrences with constant coefficients, signature (6,-9,2).
Formula
a(0)=1, a(1)=3, a(2)=10, a(n)=6a(n-1)-9a(n-2)+2a(n-3), n>2.
a(n) = 2^n/3+(2+sqrt(3))(2+sqrt(3))^n/6+(2-sqrt(3))(2-sqrt(3))^n/6.
a(n) = A087944(n+1)/2.
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