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Search: id:A080871
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| A080871 |
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a(n)*a(n+3) - a(n+1)*a(n+2) = 3, given a(0)=a(1)=1, a(2)=4. |
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+0
6
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| 1, 1, 4, 7, 31, 55, 244, 433, 1921, 3409, 15124, 26839, 119071, 211303, 937444, 1663585, 7380481, 13097377, 58106404, 103115431, 457470751, 811826071, 3601659604, 6391493137, 28355806081, 50320119025, 223244789044
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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a(n) = (3 + a(n-1)*a(n-2))/a(n-3) for n>2.
G.f.: (-x^3 - 4*x^2 + x + 1)/(x^4 - 8*x^2 + 1)
a(n+4)=8*a(n+2)-a(n) [From Richard Choulet (richardchoulet(AT)yahoo.fr), Dec 04 2008]
a(n) = (0.25 + sqrt(10)/20)*(sqrt(4 + sqrt(15)))^n + (0.25 + sqrt(10)/20)*(sqrt(4 - sqrt(15)))^n + ( - 1/20*10^(1/2) + 1/4)*( - sqrt(4 + sqrt(15)))^n + ( - 1/20*10^(1/2) + 1/4)*( - (sqrt(4 - sqrt(15))))^n [From Richard Choulet (richardchoulet(AT)yahoo.fr), Dec 06 2008]
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CROSSREFS
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Cf. A001519, A079496, A080872, A080873, A080874, A080875.
Bisections are A001091 and A070997.
Sequence in context: A149088 A047004 A030689 this_sequence A102666 A123801 A156228
Adjacent sequences: A080868 A080869 A080870 this_sequence A080872 A080873 A080874
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Feb 22 2003
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