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A373279
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Expansion of Sum_{k>=0} x^(3^k) / (1 - 3*x^(3^k)).
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5
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1, 3, 10, 27, 81, 246, 729, 2187, 6571, 19683, 59049, 177174, 531441, 1594323, 4783050, 14348907, 43046721, 129140409, 387420489, 1162261467, 3486785130, 10460353203, 31381059609, 94143181014, 282429536481, 847288609443, 2541865834900, 7625597484987
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f. A(x) satisfies A(x) = x/(1 - 3*x) + A(x^3).
If n == 0 (mod 3), a(n) = 3^n + a(n/3) otherwise a(n) = 3^n.
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PROG
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(PARI) b(n, k) = sumdiv(n, d, (gcd(d, k)==1)*(moebius(d)*k^(n/d)))/(k*n);
a(n, k=3) = sumdiv(n, d, d*b(d, k));
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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