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A032695 Exactly 5 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a prime. 1
1, 7, 9, 39, 63, 77, 83, 221, 229, 237, 521, 547, 689, 719, 733, 741, 803, 861, 907, 1283, 1647, 2003, 2051, 2073, 2467, 2727, 3003, 3063, 3331, 3487, 3597, 3609, 3629, 3719, 3773, 3857, 3997, 4421, 4449, 4499, 4747, 4919, 5083, 5439, 5541 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

If a(n) = 77 then we find '2'77, '5'77, '6'77, '8'77 and '9'77 to be primes.

MATHEMATICA

Select[Range[5600], Count[Table[n*10^IntegerLength[#]+#, {n, 9}], _?PrimeQ] == 5&] (* Harvey P. Dale, Apr 07 2015 *)

CROSSREFS

Sequence in context: A082536 A057590 A140787 * A007449 A189053 A067649

Adjacent sequences:  A032692 A032693 A032694 * A032696 A032697 A032698

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, May 15 1998

STATUS

approved

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Last modified December 10 15:32 EST 2016. Contains 279003 sequences.