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A027022
a(n) = Sum_{k=floor((n+1)/2)..n} T(k,n-k); i.e., a(n) is n-th diagonal sum of left-justified array T given by A027011.
1
1, 3, 4, 7, 11, 15, 26, 34, 57, 79, 123, 181, 269, 406, 597, 900, 1332, 1991, 2968, 4414, 6596, 9805, 14639, 21792, 32488, 48418, 72130, 107532, 160191, 238776, 355785, 530211, 790156, 1177431, 1754739, 2614807, 3896754, 5806922, 8653577, 12895791
OFFSET
1,2
LINKS
FORMULA
G.f.: x*(-x^4-3x^3+x^2+3x+1)/((1-x^2)*(1-2x^2-x^3+x^4)).
MATHEMATICA
CoefficientList[Series[(-x^4 - 3 x^3 + x^2 + 3 x + 1) / ((1 - x^2) (1 - 2 x^2 - x^3 + x^4)), {x, 0, 60}], x] (* Vincenzo Librandi, Aug 03 2017 *)
CROSSREFS
Cf. A027011.
Sequence in context: A050120 A039010 A127208 * A120365 A166375 A177041
KEYWORD
nonn
STATUS
approved