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A213842
Principal diagonal of the convolution array A213841.
3
1, 24, 101, 264, 545, 976, 1589, 2416, 3489, 4840, 6501, 8504, 10881, 13664, 16885, 20576, 24769, 29496, 34789, 40680, 47201, 54384, 62261, 70864, 80225, 90376, 101349, 113176, 125889, 139520, 154101, 169664
OFFSET
1,2
FORMULA
a(n) = (2*n - 15*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*(1 + 20*x + 11*x^2) and g(x) = (1-x)^4.
MATHEMATICA
(See A213841.)
CROSSREFS
Cf. A213841.
Sequence in context: A233405 A297798 A048529 * A333033 A269047 A182675
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jul 05 2012
STATUS
approved