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A131028
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Periodic sequence (7, 4, 1, 1, 4, 7).
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10
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7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1, 1, 4, 7, 7, 4, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Fourth column of triangular array T defined in A131022.
a(n) = A084104(n+3).
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (2,-2,1).
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FORMULA
| a(1) = a(6) = 7, a(2) = a(5) = 4, a(3) = a(4) = 1; for n > 6, a(n) = a(n-6).
G.f.: (7-10*x+7*x^2)/((1-x)*(1-x+x^2)).
a(n)=1/30*{8*(n mod 6)-7*[(n+1) mod 6]-7*[(n+2) mod 6]+8*[(n+3) mod 6]+23*[(n+4) mod 6]+23*[(n+5) mod 6]}, with n>=0. - Paolo P. Lava (paoloplava(AT)gmail.com), Jun 19 2007
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PROG
| (PARI) {m=105; for(n=1, m, r=(n-1)%6; print1(if(r==0||r==5, 7, if(r==1||r==4, 4, 1)), ", "))}
(MAGMA) m:=105; [ [7, 4, 1, 1, 4, 7][(n-1) mod 6 + 1]: n in [1..m] ];
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CROSSREFS
| Cf. A131022, A084104. Other columns of T are in A088911, A131026, A131027, A131029, A131030.
Sequence in context: A082665 A011101 A021935 * A010138 A199157 A010508
Adjacent sequences: A131025 A131026 A131027 * A131029 A131030 A131031
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KEYWORD
| nonn,easy
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), following a suggestion of Paul Curtz (bpcrtz(AT)free.fr), Jun 10 2007
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