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Search: id:A097636
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| A097636 |
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Odd numbers between the primes nearest the average that are not themselves primes. |
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+0
1
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| 9, 15, 21, 27, 35, 39, 45, 51, 57, 65, 69, 77, 81, 87, 93, 99, 105, 111, 121, 129, 135, 145, 155, 161, 165, 171, 177, 187, 195, 205, 217, 225, 231, 237, 247, 255, 261, 267, 275, 279, 289, 301, 309, 315, 325, 335, 343, 351, 357, 363, 371, 377, 381, 387, 393, 399
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = 2*n-1 if not prime and near the average of two primes
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MATHEMATICA
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digits=200 (* find odd numbers between the primes nearest the average*) a=Table[If[(Mod[(Prime[n+1]+Prime[n])/2, 2]==1)&&( PrimeQ[(Prime[n+1]+Prime[n])/2]==False)&&( PrimeQ[(Prime[n+1]+Prime[n])/2+1]==False), (Prime[n+1]+Prime[n])/ 2, (Prime[n+1]+Prime[n])/2+1], {n, 2, digits}] b=Table[Prime[n], {n, 1, digits}] (* eliminate the primes from the sequence *) aa=Complement[a, b]
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CROSSREFS
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Adjacent sequences: A097633 A097634 A097635 this_sequence A097637 A097638 A097639
Sequence in context: A107987 A031879 A063139 this_sequence A007962 A061254 A096788
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KEYWORD
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nonn,uned
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AUTHOR
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Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Sep 20 2004
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