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A017197
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a(n) = 9*n + 3.
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19
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3, 12, 21, 30, 39, 48, 57, 66, 75, 84, 93, 102, 111, 120, 129, 138, 147, 156, 165, 174, 183, 192, 201, 210, 219, 228, 237, 246, 255, 264, 273, 282, 291, 300, 309, 318, 327, 336, 345, 354, 363, 372, 381, 390, 399, 408, 417, 426, 435, 444, 453, 462, 471, 480
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OFFSET
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0,1
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COMMENTS
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LINKS
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FORMULA
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a(n) = a(n-1) + 9.
Sum_{n>=0} (-1)^n / a(n) = (Pi / sqrt(3) + log(2))/9.
G.f.: 3*(1+2*x)/(1-x)^2. (End)
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MAPLE
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MATHEMATICA
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LinearRecurrence[{2, -1}, {3, 12}, 80] (* or *) NestList[#+9&, 3, 80] (* Harvey P. Dale, Jan 22 2023 *)
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PROG
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(Sage) [i+3 for i in range(480) if gcd(i, 9) == 9] # Zerinvary Lajos, May 20 2009
(Haskell)
a017197 = (+ 3) . (* 9)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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