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Search: id:A146160
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| A146160 |
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Period 4 sequence (1, 4, 1, 16) |
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+0
2
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| 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1, 4, 1, 16, 1
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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1) Continued fraction of (8 + Sqrt[78])/14 2) GCD[4 k - k^2, 5 k^2, 20 k - 20 k^2, 16 - 32 k + 16 k^2] k=1,2,3,...
Contribution from Artur Jasinski (grafix(AT)csl.pl), Oct 29 2008: (Start)
a(n)=1 when n congruent to 1 or 3 mod 4
a(n)=4 when n congruent to 2 mod 4
a(n)=16 when n congruent to 0 mod 4
(End)
a(n+4)=a(n); a(n)=4.5*(-1)^(n+1) + 5.5 + 6*cos(Pi*(n+1)/2) ; o.g.f f(z)=a(0)+a(1)*z+...=(1+4*+z^2+16*z^3)/(1-z^4) [From Richard Choulet (richardchoulet(AT)yahoo.fr), Nov 03 2008]
a(n)=(1/6)*{28*(n mod 4)-17*[(n+1) mod 4]+10*[(n+2) mod 4]+[(n+3) mod 4]}, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 06 2008]
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MATHEMATICA
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Table[GCD[4 k - k^2, 5 k^2, 20 k - 20 k^2, 16 - 32 k + 16 k^2], {k, 1, 100}]
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CROSSREFS
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A010156
A145996 [From Artur Jasinski (grafix(AT)csl.pl), Oct 29 2008]
Sequence in context: A124029 A056920 A123382 this_sequence A059222 A117292 A062780
Adjacent sequences: A146157 A146158 A146159 this_sequence A146161 A146162 A146163
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski (grafix(AT)csl.pl), Oct 27 2008
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