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Search: id:A133307
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| A133307 |
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(1/n)*Sum[i=0..n-1,C(n,i)*C(n,i-1)*6^i*7^(n-i)], a(0)=1 . |
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5
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OFFSET
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0,2
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COMMENT
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Seventh column of array A103209 .
The Hankel transform of this sequence is 42^C(n+1,2). - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 28 2007
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FORMULA
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G.f.: [1-z-(z^2-26z+1)^(1/2)]/(12z). a(n) = Sum_{k, 0<=k<=n}A088617(n,k)*6^k . a(n) = Sum_{k, 0<=k<=n} A060693(n,k)*6^(n-k). a(n) = Sum_{k, 0<=k<=n}C(n+k, 2k)6^k*C(k), C(n) given by A000108 .
a(0)=1, a(n)=a(n-1)+6*Sum_{k, 0<=k<=n-1}a(k)*a(n-1-k) . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 23 2007
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CROSSREFS
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Cf. A000108 A060693 A103209 A103210 A103211.
Sequence in context: A156712 A004368 A130978 this_sequence A151833 A113372 A131940
Adjacent sequences: A133304 A133305 A133306 this_sequence A133308 A133309 A133310
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KEYWORD
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nonn
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AUTHOR
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Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 18 2007
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