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A271859
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Six steps forward, five steps back.
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5
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0, 1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 6, 7, 6, 5, 4, 3, 2, 3, 4, 5, 6, 7, 8, 7, 6, 5, 4, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 6, 7, 8, 9, 10, 11, 10, 9, 8, 7, 6, 7, 8, 9, 10, 11, 12, 11, 10, 9, 8, 7, 8, 9, 10, 11
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refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,0,0,1,-1).
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FORMULA
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a(n) = a(n-1) + a(n-11) - a(n-12) for n>11.
a(n) = Sum_{i=1..n} (-1)^floor((2*i-2)/11).
G.f.: x*(1+x+x^2+x^3+x^4+x^5-x^6-x^7-x^8-x^9-x^10) / ((1-x)^2*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10)). - Colin Barker, Apr 16 2016
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MAPLE
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A271859:=n->add((-1)^floor((2*i-2)/11), i=1..n): seq(A271859(n), n=0..200);
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MATHEMATICA
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Table[Sum[(-1)^Floor[(2 i - 2)/11], {i, n}], {n, 0, 100}]
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PROG
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(PARI) concat(0, Vec(x*(1+x+x^2+x^3+x^4+x^5-x^6-x^7-x^8-x^9-x^10) / ((1-x)^2*(1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10)) + O(x^50))) \\ Colin Barker, Apr 16 2016
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CROSSREFS
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Cf. A008611 (one step back, two steps forward).
Cf. A058207 (three steps forward, two steps back).
Cf. A260644 (four steps forward, three steps back).
Cf. A271800 (five steps forward, four steps back).
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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