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A131534
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Period 3: repeat 1 2 1.
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15
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1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Partial sums of A106510 . Inverse binomial transform of A024495 (without leading zeros). [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 26 2008]
a(n) = A130196(n)-A022003(n) = A080425(n)-A130196(n)+2 = A153727(n)/A130196(n). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 12 2009]
Continued fraction expansion of A177346, (1+sqrt(10))/3. [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 07 2010]
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (0,0,1).
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FORMULA
| a(n)=(1/9)*{4*(n mod 3)+7*[(n+1) mod 3]+[(n+2) mod 3]}, with n>=0. - Paolo P. Lava (paoloplava(AT)gmail.com), Aug 28 2007
G.f.: (x+1)^2/((1-x)*(x^2+x+1)). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 14 2007
a(n)=4/3+(2/3)*cos(2*pi*(n+2)/3) - Jaume Oliver Lafont (joliverlafont(AT)gmail.com), May 09 2008
a(n)=A101825(n+1). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 13 2008
a(n)=4/3+1/3*(-1/2-(1/2*I)*sqrt(3))^(-2)*(-1/2-(1/2*I)*sqrt(3))^n+1/3*(-1/2+(1/2*I) *sqrt(3))^(-2)*(-1/2+(1/2*I)*sqrt(3))^n+1/3*(-1/2-(1/2*I)*sqrt(3))^n+1/3*(-1/2 +(1/2*I)*sqrt(3))^n+2/3*(-1/2-(1/2*I)*sqrt(3))^(-1)*(-1/2-(1/2*I)*sqrt(3))^n+2/3 *(-1/2+(1/2*I)*sqrt(3))^(-1)*(-1/2+(1/2*I)*sqrt(3))^n, with n>=0 and I=sqrt(-1) [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 27 2008]
a(n)=GCD(F(n)^2+F(n+1)^2,F(n)+F(n+1)), F(n)=A000045(n) [From Gary Detlefs, Dec 29 2010]
a(n)= 2-[(n+2)^2 mod 3]. [From Gary Detlefs, Oct 13 2011]
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PROG
| (PARI) a(n)=1+(n%3==1) [From Jaume Oliver Lafont (joliverlafont(AT)gmail.com), Mar 20 2009]
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CROSSREFS
| A167808. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 12 2009]
Sequence in context: A087204 A101825 A177702 * A061347 A115579 A115573
Adjacent sequences: A131531 A131532 A131533 * A131535 A131536 A131537
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KEYWORD
| nonn,easy
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AUTHOR
| Paul Curtz (bpcrtz(AT)free.fr), Aug 26 2007
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