**a(n) = 2*a(n-1) + 2*a(n-3) + a(n-4), a(0) = 1, a(1) = 4, a(2) = 9, a(3) = 20.**

*1, 4, 9, 20, 49, 120, 289, 696, 1681, 4060, 9801, 23660, 57121, 137904, 332929*

*1 seqfan posts*

Index of A-numbers in seqfan: by ascending order by month by frequency by keyword

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