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Search: id:A090871
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| A090871 |
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Numbers n such that the six numbers 1*prime(n)*prime(n+1), prime(n)*1*prime(n+1), prime(n)*prime(n+1)*1, 1*prime(n-1)*prime(n), prime(n-1)*1*prime(n) and prime(n-1)*prime(n)*1 are primes. |
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1
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| 589407, 2372675, 5609052, 5698663, 12353466, 12534100, 14155932, 24208353, 25303609, 24208353, 25303609
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(4)=5698663 because prime(5698662)=98842171, prime(5698663)=98842223 and
prime(5698664)=98842231 and the six numbers:
19884217198842223, 98842171198842223, 98842171988422231,
19884222398842231, 98842223198842231 and 98842223988422311
are primes.
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MATHEMATICA
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v={}; Do[If[PrimeQ[FromDigits[Join[{1}, IntegerDigits[Prime[k-1]], IntegerDigits [Prime[k]]]]]&&PrimeQ[FromDigits[Join[IntegerDigits[Prime[k-1]], {1}, IntegerDigits[Prime[k]]]]]&&PrimeQ[FromDigits[Join[IntegerDigits [Prime[k-1]], IntegerDigits[Prime[k]], {1}]]]&& PrimeQ[FromDigits [Join[{1}, IntegerDigits[Prime[k]], IntegerDigits[Prime[k+1]]]]] &&PrimeQ[FromDigits[Join[IntegerDigits[Prime[k]], {1}, IntegerDigits[ Prime[k+1]]]]]&& PrimeQ[FromDigits[Join[IntegerDigits[Prime[k]], IntegerDigits[Prime[k+1]], {1}]]], v=Append[v, k]; Print[v]], {k, 2, 3*10^7}]; v
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CROSSREFS
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Sequence in context: A050518 A104962 A100386 this_sequence A022257 A106779 A106780
Adjacent sequences: A090868 A090869 A090870 this_sequence A090872 A090873 A090874
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KEYWORD
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more,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jan 25 2004
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