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Search: id:A100233
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| 1, 3, 17, 75, 321, 1363, 5777, 24475, 103681, 439203, 1860497, 7881195, 33385281, 141422323, 599074577, 2537720635, 10749957121, 45537549123, 192900153617, 817138163595, 3461452808001, 14662949395603, 62113250390417
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OFFSET
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0,2
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FORMULA
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a(n) = 4*a(n-1) + a(n-2) + 4 for n>1, with a(0)=1, a(1)=3. G.f.: Sum_{n>=1} a(n)*x^n/n = log((1-x)/(1-4*x-x^2)).
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PROGRAM
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(PARI) a(n)=if(n==0, 1, n*polcoeff(log((1-x)/(1-4*x-x^2)+x*O(x^n)), n))
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CROSSREFS
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Main diagonal of triangle A100232.
Cf. A100230, A100232.
Equals A014448(n) - 1.
Sequence in context: A128948 A049181 A142868 this_sequence A015525 A062224 A093568
Adjacent sequences: A100230 A100231 A100232 this_sequence A100234 A100235 A100236
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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), Nov 29 2004
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EXTENSIONS
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New definition from Ralf Stephan, Dec 01, 2004
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