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Search: id:A129508
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| A129508 |
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Numbers n such that 3 and 5 do not divide binomial(2n,n). |
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2
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| 0, 1, 10, 12, 27, 30, 31, 36, 37, 252, 255, 256, 280, 282, 756, 757, 760, 810, 811, 3160, 3162, 3186, 3187, 3250, 3252, 3276, 3277, 3280, 6561, 6562, 6885, 6886, 6912, 6925, 7536, 7537, 7560, 7561, 7626, 7627, 7650, 7651, 19686, 19687, 20007, 20010, 20011
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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The Erdos paper proves that for any two odd primes p and q, there are an infinite number of n for which gcd(p*q,binomial(2n,n))=1; i.e., p and q do not divide binomial(2n,n).
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REFERENCES
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P. Erdos, R. L. Graham, I. Z. Russa and E. G. Straus, On the prime factors of C(2n,n), Math. Comp. 29 (1975), 83-92.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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FORMULA
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Intersection of A005836 and A037453.
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MATHEMATICA
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lim=10000; Intersection[Table[FromDigits[IntegerDigits[k, 2], 3], {k, 0, lim}], Table[FromDigits[IntegerDigits[k, 3], 5], {k, 0, lim}]]
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CROSSREFS
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Cf. A030979 (n such that 3, 5 and 7 do not divide binomial(2n, n)).
Sequence in context: A140972 A108901 A073083 this_sequence A015728 A080470 A087217
Adjacent sequences: A129505 A129506 A129507 this_sequence A129509 A129510 A129511
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KEYWORD
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nonn
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AUTHOR
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T. D. Noe (noe(AT)sspectra.com), Apr 18 2007
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