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Search: id:A100003
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| A100003 |
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Prime numbers n such that the concatenation of all odd primes up through n in decreasing order is prime. |
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4
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OFFSET
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1,1
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COMMENT
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Next term is greater than 4400-th prime and the prime corresponding to the next term has more than 20000 digits. Number of digits of primes corresponding to the six known terms of the sequence are respectively 1,2,9,43,198 & 4202.
We can see the prime corresponding to 383 (the 5-th term of the sequence) in the page related to puzzle 8 of the website of Carlos Rivera.
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LINKS
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C. Rivera, Primes by Listing.
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EXAMPLE
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17 is in the sequence because 17.13.11.7.5.3 is prime (dot between numbers means concatenation).
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MATHEMATICA
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Do[If[PrimeQ[(v={}; Do[v=Join[v, IntegerDigits[Prime[n-j+1]]], {j, n-1}]; FromDigits[v])], Print[Prime[n]]], {n, 2, 4413}]
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CROSSREFS
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Cf. A046284, A099070, A099071, A099073.
Adjacent sequences: A100000 A100001 A100002 this_sequence A100004 A100005 A100006
Sequence in context: A137460 A102295 A102846 this_sequence A114161 A087858 A084723
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KEYWORD
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base,more,nonn,nice
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)math.ui.ac.ir), Nov 06 2004
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