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A000999
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5-adic valuation of binomial(2*n,n): largest k such that 5^k divides binomial(2*n, n).
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1
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0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 3, 3, 2, 2, 2, 3, 3, 2, 2, 2, 3, 3, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1
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OFFSET
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0,14
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LINKS
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FORMULA
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MATHEMATICA
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Table[IntegerExponent[Binomial[2*n, n], 5], {n, 0, 100}] (* T. D. Noe, Jun 21 2012 *)
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PROG
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(PARI) a(n)=if(n<0, 0, valuation(binomial(2*n, n), 5))
(PARI) a(n) = my(v=digits(n, 5), c=0); sum(i=0, #v-1, c=(c+v[#v-i]>=3)); \\ Kevin Ryde, Mar 07 2023
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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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