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Search: id:A067316
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| A067316 |
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Number of values of j, 0<=j<=n, such that 1+C(n,j) is prime, where C(n,j) is the binomial coefficient n choose j. |
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2
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| 1, 2, 3, 2, 5, 4, 4, 2, 5, 6, 6, 6, 6, 4, 5, 2, 6, 8, 8, 6, 6, 4, 4, 2, 11, 4, 4, 8, 8, 8, 4, 2, 6, 4, 8, 14, 8, 4, 5, 6, 12, 10, 4, 6, 9, 8, 8, 4, 6, 8, 6, 10, 6, 6, 12, 6, 8, 4, 12, 2, 6, 8, 4, 2, 8, 18, 8, 2, 6, 14, 10, 16, 10, 6, 4, 10, 13, 8, 12, 4, 8, 2, 8, 14, 2, 6, 4, 10, 10, 16, 10, 10, 9
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OFFSET
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0,2
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EXAMPLE
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For n=8, the primes are 2,29,71,29,2, so a(n)=5. a(n)=6 for n=9,10,11,12. Also, a(n)=10 for n=149,...,154.
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MATHEMATICA
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a[n_] := Count[Table[PrimeQ[Binomial[n, w]+1], {w, 0, n}], True]
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CROSSREFS
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Sequence in context: A075861 A141658 A089587 this_sequence A127433 A055573 A072969
Adjacent sequences: A067313 A067314 A067315 this_sequence A067317 A067318 A067319
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jan 15 2002
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