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Search: id:A090139
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| A090139 |
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a(n)=10a(n-1)-20a(n-2), a(0)=1,a(1)=5. |
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+0
4
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| 1, 5, 30, 200, 1400, 10000, 72000, 520000, 3760000, 27200000, 196800000, 1424000000, 10304000000, 74560000000, 539520000000, 3904000000000, 28249600000000, 204416000000000, 1479168000000000, 10703360000000000
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Fifth binomial transform of (1,0,5,0,25,0,....)
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FORMULA
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a(n)=(5-sqrt(5))^n/2+(5+sqrt(5))^n/2; a(n)=sum{k=0..floor(n/2), C(n, 2k)5^(n-k)}=sum{k=0..n, C(n, k)5^(n-k/2)(1+(-1)^k)/2}.
a(n) = Sum_{k, 0<=k<=n}5^k*A098158(n,k) . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 04 2006
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CROSSREFS
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Sequence in context: A034164 A103433 A081015 this_sequence A107265 A128328 A118346
Adjacent sequences: A090136 A090137 A090138 this_sequence A090140 A090141 A090142
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Nov 22 2003
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