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0, 1, 2, 0, 1, 2, 3, 1, 2, 3, 4, 2, 3, 4, 5, 3, 4, 5, 6, 4, 5, 6, 7, 5, 6, 7, 8, 6, 7, 8, 9, 7, 8, 9, 10, 8, 9, 10, 11, 9, 10, 11, 12, 10, 11, 12, 13, 11, 12, 13, 14, 12, 13, 14, 15, 13, 14, 15, 16, 14, 15, 16, 17, 15, 16, 17, 18, 16, 17, 18, 19, 17, 18, 19, 20, 18, 19, 20, 21, 19, 20, 21
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,3
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COMMENTS
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Also array read by rows, with four columns, in which row n lists n, n+1, n+2, n. - Omar E. Pol, Jan 22 2012
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LINKS
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FORMULA
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a(n) = floor(n/4) + (n mod 4) mod 3.
G.f.: x*(1+x-2*x^2+x^3)/((1+x)*(1+x^2)*(1-x)^2).
a(n) = (1/8)*(2*n-6*(-1)^(n*(n+1)/2)+3*(-1)^n+3). (End)
a(n) = a(n-1)+a(n-4)-a(n-5).
a(n) = 1 + floor((n-7)/4) + ((n-7) mod 4). (End)
a(n) = (2*n+3-6*cos(n*Pi/2)+3*cos(n*Pi)+6*sin(n*Pi/2))/8. - Wesley Ivan Hurt, Oct 01 2017
Sum_{n>=4} (-1)^(n+1)/a(n) = 1/2. - Amiram Eldar, Oct 04 2022
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EXAMPLE
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Array begins:
0, 1, 2, 0;
1, 2, 3, 1;
2, 3, 4, 2;
3, 4, 5, 3;
4, 5, 6, 4;
5, 6, 7, 5;
6, 7, 8, 6;
7, 8, 9, 7;
(End)
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MAPLE
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MATHEMATICA
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Table[(1/8)*(2*n - 6*(-1)^(n*(n + 1)/2) + 3*(-1)^n + 3), {n, 0, 100}] (* Wesley Ivan Hurt, Apr 12 2015 *)
LinearRecurrence[{1, 0, 0, 1, -1}, {0, 1, 2, 0, 1}, 90] (* Harvey P. Dale, Feb 02 2020 *)
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PROG
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(Magma) [Integers()!(2*n-6*(-1)^(n*(n+1)/2)+3*(-1)^n+3)/8: n in [0..81]]; // Bruno Berselli, Sep 28 2011
(PARI) vector(80, n, n--; 1 + (n-7)\4 + ((n-7) % 4)) \\ Michel Marcus, Apr 13 2015
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CROSSREFS
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KEYWORD
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nonn,tabf,easy
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AUTHOR
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STATUS
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approved
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