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A084569
Partial sums of A084570.
1
1, 3, 9, 21, 44, 82, 142, 230, 355, 525, 751, 1043, 1414, 1876, 2444, 3132, 3957, 4935, 6085, 7425, 8976, 10758, 12794, 15106, 17719, 20657, 23947, 27615, 31690, 36200, 41176, 46648, 52649, 59211, 66369, 74157, 82612, 91770, 101670, 112350, 123851
OFFSET
0,2
FORMULA
a(n)=(-1)^n/8 + (n^4+6n^3+17n^2+30n+21)/24; a(n)=sum(sum(sum(i+(-1)^i, i, 0, j), j, 0, k), k, 0, n).
MATHEMATICA
Accumulate[LinearRecurrence[{3, -2, -2, 3, -1}, {1, 2, 6, 12, 23}, 50]] (* or *) LinearRecurrence[{4, -5, 0, 5, -4, 1}, {1, 3, 9, 21, 44, 82}, 50] (* Harvey P. Dale, Nov 12 2014 *)
CROSSREFS
Sequence in context: A011843 A080549 A175006 * A192970 A110964 A107351
KEYWORD
easy,nonn
AUTHOR
Paul Barry, May 31 2003
STATUS
approved