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A014915
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a(1)=1, a(n)=n*3^(n-1)+a(n-1).
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10
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1, 7, 34, 142, 547, 2005, 7108, 24604, 83653, 280483, 930022, 3055786, 9964519, 32285041, 104029576, 333612088, 1065406345, 3389929279, 10750918570, 33996147910, 107218620331, 337346390797, 1059110761804, 3318547053652
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..600
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FORMULA
| a(n) = ((2*n-1)*3^n + 1)/4 = 7*a(n-1) -15*a(n-2) +9*a(n-3) = 1 + 2*3 + 3*3^2 + .. + n*3^(n-1) = a(n-1) + A027471(n+1) - Henry Bottomley (se16(AT)btinternet.com), Dec 18 2000
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MATHEMATICA
| Join[{a=1, b=7}, Table[c=6*b-9*a+1; a=b; b=c, {n, 60}]] (*From Vladimir Joseph Stephan Orlovsky, Feb 06 2011*)
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PROG
| (MAGMA) [((2*n - 1)*3^n + 1)/4: n in [1..30]]; // Vincenzo Librandi, Jun 09 2011
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CROSSREFS
| Cf. A059045.
Cf. A027261, A064017, A079272.
Sequence in context: A000418 A055852 A122611 * A137747 A094256 A005023
Adjacent sequences: A014912 A014913 A014914 * A014916 A014917 A014918
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KEYWORD
| nonn,easy
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AUTHOR
| Olivier Gerard (olivier.gerard(AT)gmail.com)
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