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Search: id:A136349
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| A136349 |
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Numbers n of the form product( prime(i), i=1..k) such that n-1 is prime. |
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+0
10
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| 6, 30, 2310, 30030, 304250263527210, 23768741896345550770650537601358310, 19361386640700823163471425054312320082662897612571563761906962414215012369856637\ 179096947335243680669607531475629148240284399976570
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Next term is too large to be included: see A006794. - M. F. Hasler, May 02 2008
This sequence is different from A121069 and A002110.
Compute the product of k consecutive sequences of prime factors 2,3,5,7,etc. where k=1,2,3,4,5,etc. Where N is preceded by prime N-1 add N to the sequence.
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FORMULA
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a(n) = A057705(n) + 1 = A034386( A006794(n) ). - M. F. Hasler, May 02 2008
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EXAMPLE
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a(3)=30 where the prime factors are 2,3,5; since N-1=29, prime, N=30 is added to the sequence.
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PROGRAM
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(PARI) c=0; t=1; vector(7, n, until( ispseudoprime( -1+t*=prime(c++)), ); t)
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CROSSREFS
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Cf. A136350 A136351 A136352 A002110 A121069.
Adjacent sequences: A136346 A136347 A136348 this_sequence A136350 A136351 A136352
Sequence in context: A130075 A066388 A088256 this_sequence A119411 A036285 A101340
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KEYWORD
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nonn
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AUTHOR
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Enoch Haga (Enokh(AT)comcast.net), Dec 25 2007
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EXTENSIONS
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Edited by M. F. Hasler (www.univ-ag.fr/~mhasler), May 02 2008, May 30 2008
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