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A227833
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3-adic valuation of A005130(n).
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3
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0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 2, 3, 5, 5, 3, 2, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 2, 3, 5, 6, 6, 7, 8, 9, 11, 13, 15, 18, 18, 15, 13, 11, 9, 8, 7, 6, 6, 5, 3, 2, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 2, 3, 5, 5, 3, 2, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 2, 3, 5, 6, 6, 7, 8, 9, 11, 13, 15, 18, 19, 18, 18, 18, 18, 19
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OFFSET
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0,12
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COMMENTS
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3^a(n) is the highest power of 3 dividing A005130(n).
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LINKS
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FORMULA
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a(n) = a(n-1) + (s(2*n-2) + s(2*n-1) - s(n-1) - s(3*n-2))/2, where s(n) = A053735(n). (End)
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MATHEMATICA
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s[n_] := Plus @@ IntegerDigits[n, 3]; a[0] = 0; a[n_] := a[n] = a[n - 1] + (s[2*n - 2] + s[2*n - 1] - s[n - 1] - s[3*n - 2])/2; Array[a, 101, 0] (* Amiram Eldar, Feb 21 2021 *)
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PROG
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(Magma) A005130:=func<i | IsZero(i) select 1 else &*[Factorial(3*k+1)/Factorial(i+k): k in [0..i-1]]>; [Valuation(A005130(n), 3): n in [0..100]]; // Bruno Berselli, Aug 05 2013
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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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