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Search: id:A057019
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| A057019 |
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Difference between n!! and the first prime after n!! + 1. |
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+0
5
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| 2, 3, 2, 3, 2, 5, 2, 5, 2, 7, 4, 11, 16, 11, 8, 17, 4, 19, 64, 17, 2, 17, 2, 13, 8, 71, 2, 61, 4, 19, 118, 59, 32, 23, 82, 19, 178, 41, 4, 101, 8, 41, 4, 59, 16, 47, 16, 131, 298, 29, 64, 31, 16, 83, 194, 31, 2, 41, 298, 53, 316, 193, 8, 67, 334, 53, 32, 43, 226, 149, 386, 37
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Analogous to the Fortunate numbers but unlike them, all entries are not prime. Many odd-indexed entries are powers of two and all even-indexed entries are primes.
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MATHEMATICA
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NextPrime[ n_Integer ] := (k=n+1; While[ !PrimeQ[ k ], k++ ]; Return[ k ]); f[ n_Integer ] := (p = n!! + 1; q = NextPrime[ p ]; Return[ q - p + 1 ]); Table[ f[ n ], {n, 1, 75} ]
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PROGRAM
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(Mupad) for n from 1 to 72 do f := n!!:a := nextprime(f+2)-f:print(a) end_for; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 22 2007
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CROSSREFS
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Adjacent sequences: A057016 A057017 A057018 this_sequence A057020 A057021 A057022
Sequence in context: A016026 A086757 A046215 this_sequence A084740 A077199 A064652
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 09 2000
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