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A073078
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Least k such that n divides C(2k,k).
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1
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1, 1, 2, 3, 3, 2, 4, 7, 5, 3, 6, 5, 7, 4, 8, 15, 9, 5, 10, 3, 5, 6, 12, 7, 13, 7, 14, 5, 15, 8, 16, 31, 6, 9, 4, 5, 19, 10, 7, 13, 21, 5, 22, 6, 8, 12, 24, 15, 25, 13, 11, 7, 27, 14, 8, 11, 11, 15, 30, 14, 31, 16, 5, 63, 8, 6, 34, 9, 14, 4, 36, 14, 37, 19, 14, 10, 6, 7, 40, 15, 41, 21
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| a(2^k)=2^k-1, if n is an odd prime a(n)=(n+1)/2 (but there are also some composite satisfying this property),
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PROG
| (PARI) a(n)=if(n<0, 0, s=1; while(binomial(2*s, s)%n>0, s++); s)
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CROSSREFS
| Sequence in context: A036465 A182865 A131469 * A034799 A008985 A138652
Adjacent sequences: A073075 A073076 A073077 * A073079 A073080 A073081
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KEYWORD
| easy,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 17 2002
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