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A213848
Principal diagonal of the convolution array A213847.
3
3, 36, 131, 320, 635, 1108, 1771, 2656, 3795, 5220, 6963, 9056, 11531, 14420, 17755, 21568, 25891, 30756, 36195, 42240, 48923, 56276, 64331, 73120, 82675, 93028, 104211, 116256, 129195, 143060, 157883, 173696
OFFSET
1,1
FORMULA
a(n) = (-4*n - 3*n^2 + 16*n^3)/3.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4).
G.f.: f(x)/g(x), where f(x) = x*(3 + 24*x + 5*x^2) and g(x) = (1-x)^4.
MATHEMATICA
(See A213841.)
CROSSREFS
Cf. A213841.
Sequence in context: A324157 A268591 A275560 * A006428 A068619 A247768
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 05 2012
STATUS
approved