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Search: id:A129978
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| A129978 |
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Numbers n such that A120265(n)=numerator( sum( 1/k!, k=1..n )) is a prime. |
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+0
1
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| 2, 3, 4, 5, 6, 7, 12, 16, 19, 21, 22, 25, 41, 114, 181, 236
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Corresponding primes are A120265[a(n)] = {3, 5, 41, 103, 1237, 433, 164611949, 35951249665217, 52255141388393, 43894318766250120011, 386270005143001056097, 53952693026046706215979, 1249584099900912571604389306768231303904375213027, ...}.
a(17)>1000 ; A120265(1000)~2.9e2564=(e-1) A061355(1000). (M. F. Hasler, Jun 18 2007)
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MATHEMATICA
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Do[ f=Numerator[ Sum[ 1/k!, {k, 1, n} ] ]; If[ PrimeQ[f], Print[{n, f}] ], {n, 1, 236} ]
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PROGRAM
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(PARI) t=0; for( n=1, 1000, if( ispseudoprime( numerator( t+=1/n!)), print( n", " ))) (M. F. Hasler, Jun 18 2007)
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CROSSREFS
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Cf. A120265, A061354, A061355.
Sequence in context: A108948 A107818 A039952 this_sequence A033079 A125745 A032990
Adjacent sequences: A129975 A129976 A129977 this_sequence A129979 A129980 A129981
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KEYWORD
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more,nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Jun 13 2007
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EXTENSIONS
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Edited by M. F. Hasler (Maximilian.Hasler(AT)gmail.com), Jun 18 2007
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