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Search: id:A084429
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| A084429 |
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n-th nonnegative integer m such that the concatenation fi(4,m)=4 m 3 m 2 m 1 is prime. (cf.A083660). |
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+0
1
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| 14, 15, 23, 25, 37, 39, 44, 54, 55, 70, 79, 88, 90, 98, 102, 118, 123, 134, 136, 143, 144, 151, 174, 182, 202, 209, 215, 226, 230, 232, 245, 254, 256, 257, 258, 262, 264, 267, 272, 284, 287, 297, 300
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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I have defined and nemed this sequence by f4i and defined other similar sequences {fni} in coments of A083660 . fni(m) is the m-th nonnegative integer k such that the ncatenation fi(n,k)=n k n-1 k ... 3 k 2 k 1 is prime. By this definition f2i=A032702.
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EXAMPLE
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a(3)=23 because 23 is the third nonnegative integer m such that fi(4,m)= (fi(4,23)=4 23 3 23 2 23 1=4233232231 is prime.
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MATHEMATICA
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Do[If[PrimeQ[FromDigits[Join[{4}, IntegerDigits[n], {3}, IntegerDigits[n], {2}, IntegerDigits[n], {1}]]], v=Insert[v, n, -1]], {n, 300}]; v
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CROSSREFS
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Cf. A083660, A032702.
Sequence in context: A047821 A085816 A090066 this_sequence A087430 A085900 A075659
Adjacent sequences: A084426 A084427 A084428 this_sequence A084430 A084431 A084432
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KEYWORD
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easy,base,uned,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)sci.ui.ac.ir), Jun 27 2003
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