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Search: id:A072684
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| A072684 |
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Expansion of (2+x+3*x^2+2*x^3+x^4)/(1-x-5*x^2+x^3+3*x^4-x^5). |
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+0
1
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| 2, 3, 16, 31, 103, 235, 674, 1669, 4526, 11595, 30769, 79885, 210226, 548623, 1439156, 3763159, 9859523, 25800519, 67566130, 176858881, 463073602, 1212259843, 3173871101, 8309086201, 21753819938, 56951673915, 149102333944
(list; graph; listen)
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OFFSET
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0,1
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REFERENCES
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S. Ramanujan, Note on a set of Simultaneous Equations, J. Indian Math. Soc., 4(1912), 94-96.
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FORMULA
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G.f.: (2+x+3*x^2+2*x^3+x^4)/(1-x-5*x^2+x^3+3*x^4-x^5).
a(n)=2*a(n-1)+3*a(n-2)-4*a(n-3)+a(n-4)+3*(-1)^n.
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PROGRAM
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(PARI) a(n)=if(n<0, 0, polcoeff((2+x+3*x^2+2*x^3+x^4)/(1-x-5*x^2+x^3+3*x^4-x^5)+x*O(x^n), n))
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CROSSREFS
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Sequence in context: A085734 A034382 A034383 this_sequence A073633 A012357 A012701
Adjacent sequences: A072681 A072682 A072683 this_sequence A072685 A072686 A072687
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KEYWORD
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nonn,easy
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AUTHOR
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Michael Somos, Jul 01, 2002
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