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A213823
Principal diagonal of the convolution array A213822.
3
4, 41, 147, 358, 710, 1239, 1981, 2972, 4248, 5845, 7799, 10146, 12922, 16163, 19905, 24184, 29036, 34497, 40603, 47390, 54894, 63151, 72197, 82068, 92800, 104429, 116991, 130522, 145058, 160635, 177289
OFFSET
1,1
FORMULA
a(n) = (-n - 3n^2 + 12*n^3)/2.
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*(4 + 25*x + 7*x^2) and g(x) = (1-x)^4.
MATHEMATICA
(See A213822.)
CROSSREFS
Cf. A213822.
Sequence in context: A119527 A074991 A294972 * A296800 A273418 A273446
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 04 2012
STATUS
approved