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A133308
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(1/n)*Sum[i=0..n-1,C(n,i)*C(n,i-1)*7^i*8^(n-i)], a(0)=1 .
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4
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OFFSET
| 0,2
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COMMENTS
| Eighth column of array A103209 .
The Hankel transform of this sequence is 56^C(n+1,2). - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 28 2007
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FORMULA
| G.f.: [1-z-(z^2-30z+1)^(1/2)]/(14z). a(n) = Sum_{k, 0<=k<=n}A088617(n,k)*7^k . a(n) = Sum_{k, 0<=k<=n} A060693(n,k)*7^(n-k). a(n) = Sum_{k, 0<=k<=n}C(n+k, 2k)7^k*C(k), C(n) given by A000108 .
a(0)=1, a(n)=a(n-1)+7*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
| Cf. A000108 A060693 A103209 A103210 A103211.
Sequence in context: A004381 A166179 A130979 * A191098 A151834 A007762
Adjacent sequences: A133305 A133306 A133307 * A133309 A133310 A133311
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KEYWORD
| nonn
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 18 2007
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