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A117917
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a(n) = 3*a(n-1) + a(n-2) + n.
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0
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1, 4, 15, 52, 175, 582, 1927, 6370, 21045, 69514, 229597, 758316, 2504557, 8272000, 27320571, 90233728, 298021771, 984299058, 3250918963, 10737055966, 35462086881, 117123316630, 386832036793, 1277619427032, 4219690317913
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Simple recursive sequence.
a(n)/a(n-1) tends to 3.30277563... = expArcSinh(3/2).
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FORMULA
| O.g.f.: -(1-x+x^2)/{(-1+x)^2 (-1+3*x+x^2)} . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 17 2008
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EXAMPLE
| a(5) = 582 = 3*a(n-1) + a(n-2) + n; = 3*175 + 52 + 5.
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MATHEMATICA
| Join[{a=1, b=4}, Table[c=3*b+a+n; a=b; b=c, {n, 2, 60}]] (*From Vladimir Joseph Stephan Orlovsky, Jan 22 2011*)
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CROSSREFS
| Sequence in context: A137213 A027853 A132894 * A192431 A161125 A027295
Adjacent sequences: A117914 A117915 A117916 * A117918 A117919 A117920
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KEYWORD
| nonn
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AUTHOR
| Gary W. Adamson (qntmpkt(AT)yahoo.com), Apr 02 2006
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 17 2008
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