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Search: id:A139814
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| A139814 |
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a(n)=a(n-1)+a(n-2)+a(n-3)+2a(n-4); a(0)=0,a(1)=1,a(2)=3,a(3)=7. |
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+0
1
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| 0, 1, 3, 7, 11, 23, 47, 95, 187, 375, 751, 1503, 3003, 6007, 12015, 24031, 48059, 96119, 192239, 384479, 768955, 1537911, 3075823, 6151647, 12303291, 24606583, 49213167, 98426335, 196852667, 393705335, 787410671, 1574821343, 3149642683
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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O.g.f.: -x(1+2x+3x^2)/((2x-1)(1+x)(x^2+1)). a(n) = (-1)^(n+1)/3 +11*2^n/15 -2*(-1)^[n/2]*A000034(n)/5 . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 24 2008
a(n)=(2/5+1/5*I)*I^n+(1/3)*(-1)^n+(11/30)*2^n+(2/5-1/5*I)*(-I)^n, with n>=1 and I=(-1)^(1/2) - Paolo P. Lava (ppl(AT)spl.at), Jun 03 2008
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CROSSREFS
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Cf. A132429.
Sequence in context: A090918 A139253 A116606 this_sequence A099902 A092284 A024459
Adjacent sequences: A139811 A139812 A139813 this_sequence A139815 A139816 A139817
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KEYWORD
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nonn
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AUTHOR
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Paul Curtz (bpcrtz(AT)free.fr), May 23 2008
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 24 2008
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