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A027010
a(n) = Sum_{k=floor((n+1)/2)..n} T(k,n-k); i.e., a(n) is the n-th diagonal sum of left-justified array T given by A026998.
1
1, 1, 2, 5, 6, 13, 17, 29, 43, 64, 100, 144, 223, 326, 492, 733, 1089, 1634, 2421, 3626, 5389, 8041, 11985, 17847, 26624, 39640, 59112, 88059, 131242, 195592, 291433, 434369, 647218, 964581, 1437374, 2142013, 3192113, 4756821
OFFSET
1,3
LINKS
FORMULA
G.f.: x*(2x^3-x^2+1)/((1-x)*(1-2x^2-x^3+x^4)).
MATHEMATICA
CoefficientList[Series[(2 x^3 - x^2 + 1) / ((1 - x) (1 - 2 x^2 - x^3 + x^4)), {x, 0, 40}], x] (* Vincenzo Librandi, Aug 03 2017 *)
CROSSREFS
Sequence in context: A325285 A323348 A181314 * A038191 A321472 A087128
KEYWORD
nonn
STATUS
approved