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A081259
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a(n) is the smallest k such that C(3n,n) divides k!.
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1
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2, 5, 7, 11, 13, 17, 19, 23, 23, 29, 31, 31, 37, 41, 43, 47, 47, 53, 53, 59, 61, 61, 67, 71, 73, 73, 79, 83, 83, 89, 89, 89, 97, 101, 103, 107, 109, 113, 113, 113, 113, 113, 127, 131, 131, 137, 139, 139, 139, 149, 151, 151, 157, 157, 163, 167, 167, 173, 173, 179, 181
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OFFSET
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1,1
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COMMENTS
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a(n) is the largest prime < 3n. More generally the smallest k such that C(mn,n) divides k! is the largest prime < mn.
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LINKS
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Table of n, a(n) for n=1..61.
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FORMULA
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a(n) = A151799(3n). - R. J. Mathar, Jul 18 2015
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MATHEMATICA
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NextPrime[3Range[70], -1] (* Harvey P. Dale, Oct 20 2011 *)
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PROG
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(PARI) a(n)=if(n<0, 0, s=1; while(k!%binomial(3*n, n)>0, k++); k)
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CROSSREFS
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Cf. A060308, A151799.
Sequence in context: A229470 A157829 A020581 * A177512 A118751 A173494
Adjacent sequences: A081256 A081257 A081258 * A081260 A081261 A081262
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre, Apr 20 2003
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STATUS
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approved
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