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A248159
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Expansion of (1 - 2*x^2)/(1 + x)^4. Third column of Riordan triangle A248156.
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3
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1, -4, 8, -12, 15, -16, 14, -8, -3, 20, -44, 76, -117, 168, -230, 304, -391, 492, -608, 740, -889, 1056, -1242, 1448, -1675, 1924, -2196, 2492, -2813, 3160, -3534, 3936, -4367, 4828, -5320, 5844, -6401, 6992, -7618, 8280, -8979, 9716
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OFFSET
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0,2
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COMMENTS
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This is the column k=2 sequence of the Riordan triangle A248156 without the leading two zeros.
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LINKS
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FORMULA
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O.g.f.: (1 - 2*x^2)/(1 + x)^4 = -1/(1 + x)^4 + 4/(1 + x)^3 -2/(1 + x)^2.
a(n) = (-1)^n*(n+1)*(6 + 7*n - n^2)/3!, n >= 0.
a(n) = -4*(a(n-1) + a(n-3)) - 6*a(n-2) - a(n-4), n >= 4, with a(0) =1, a(1) = -4, a(2) = 8 and a(3) = -12.
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MAPLE
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MATHEMATICA
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Table[(-1)^(n + 1)*(n + 1)*(n^2 - 7*n - 6)/3!, {n, 0, 50}] (* Wesley Ivan Hurt, Oct 07 2014 *)
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PROG
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(Magma) [(-1)^(n+1)*(n+1)*(n^2-7*n-6)/Factorial(3) : n in [0..50]]; // Wesley Ivan Hurt, Oct 07 2014
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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