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A090871 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. 0
589407, 2372675, 5609052, 5698663, 12353466, 12534100, 14155932, 24208353, 25303609, 24208353, 25303609 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..11.

EXAMPLE

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.

MATHEMATICA

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

CROSSREFS

Sequence in context: A206222 A202160 A216927 * A237493 A232361 A236736

Adjacent sequences:  A090868 A090869 A090870 * A090872 A090873 A090874

KEYWORD

more,nonn

AUTHOR

Farideh Firoozbakht, Jan 25 2004

STATUS

approved

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Last modified May 23 10:51 EDT 2022. Contains 353975 sequences. (Running on oeis4.)