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A109047
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a(n) = lcm(n, 6).
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5
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0, 6, 6, 6, 12, 30, 6, 42, 24, 18, 30, 66, 12, 78, 42, 30, 48, 102, 18, 114, 60, 42, 66, 138, 24, 150, 78, 54, 84, 174, 30, 186, 96, 66, 102, 210, 36, 222, 114, 78, 120, 246, 42, 258, 132, 90, 138, 282, 48, 294, 150, 102, 156, 318, 54, 330, 168, 114, 174, 354
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OFFSET
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0,2
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,2,0,0,0,0,0,-1).
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FORMULA
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a(n) = n*6/gcd(n, 6).
G.f.: 6*x*(1+x+x^2+2*x^3+5*x^4+x^5+5*x^6+2*x^7+x^8+x^9+x^10) / ( (x-1)^2*(1+x)^2*(1+x+x^2)^2*(x^2-x+1)^2 ). (End)
Sum_{k=1..n} a(k) ~ (7/4) * n^2. - Amiram Eldar, Nov 26 2022
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MATHEMATICA
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PROG
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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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STATUS
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approved
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