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A000750
Expansion of bracket function.
(Formerly M3851 N1576)
9
1, -5, 15, -35, 70, -125, 200, -275, 275, 0, -1000, 3625, -9500, 21250, -42500, 76875, -124375, 171875, -171875, 0, 621875, -2250000, 5890625, -13171875, 26343750, -47656250, 77109375, -106562500, 106562500, 0
OFFSET
0,2
COMMENTS
It appears that the (unsigned) sequence is identical to its 5th-order absolute difference. - John W. Layman, Sep 23 2003
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
FORMULA
G.f.: 1/((1+x)^5-x^5).
a(n) = (-1)^n * Sum_{k=0..floor(n/5)} (-1)^k * binomial(n+4,5*k+4). - Seiichi Manyama, Mar 21 2019
MATHEMATICA
LinearRecurrence[{-5, -10, -10, -5}, {1, -5, 15, -35}, 30] (* Jean-François Alcover, Feb 11 2016 *)
PROG
(PARI) Vec(1/((1+x)^5-x^5) + O(x^40)) \\ Michel Marcus, Feb 11 2016
(PARI) {a(n) = (-1)^n*sum(k=0, n\5, (-1)^k*binomial(n+4, 5*k+4))} \\ Seiichi Manyama, Mar 21 2019
CROSSREFS
Column 5 of A307047.
Sequence in context: A373463 A290447 A360051 * A289389 A008487 A000743
KEYWORD
sign,easy
STATUS
approved