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A215417
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Primes that remain prime when a single zero digit is inserted between any two adjacent digits.
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30
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11, 13, 17, 19, 37, 41, 53, 59, 61, 67, 71, 79, 89, 97, 109, 113, 131, 149, 191, 197, 227, 239, 269, 281, 283, 337, 367, 379, 383, 401, 421, 449, 457, 499, 503, 509, 587, 607, 673, 701, 719, 727, 739, 757, 809, 811, 887, 907, 929, 991, 1009, 1061, 1093, 1103
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history;
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internal format)
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OFFSET
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1,1
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LINKS
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Giovanni Resta, Table of n, a(n) for n = 1..4300 (terms a(1)-a(372) from Paolo P. Lava, terms a(373)-a(700) from Vincenzo Librandi)
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EXAMPLE
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399617 is prime and also 3996107, 3996017, 3990617, 3909617, 3099617.
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MAPLE
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A215417:=proc(q)
local a, b, c, i, n, ok;
for n from 5 to q do
a:=ithprime(n); b:=0; while a>0 do b:=b+1; a:=trunc(a/10); od;
a:=ithprime(n); ok:=1;
for i from 1 to b-1 do
c:=a+9*10^i*trunc(a/10^i); if not isprime(c) then ok:=0; break; fi;
od;
if ok=1 then print(ithprime(n)); fi;
od; end:
A215417(1000);
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MATHEMATICA
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Select[Prime[Range[5, 200]], And@@PrimeQ[Table[FromDigits[Insert[ IntegerDigits[ #], 0, n]], {n, 2, IntegerLength[#]}]]&] (* Harvey P. Dale, Feb 23 2014 *)
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PROG
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(PARI) is(n)=my(v=concat([""], digits(n))); for(i=2, #v-1, v[1]=Str(v[1], v[i]); v[i]=0; if(i>2, v[i-1]=""); if(!isprime(eval(concat(v))), return(0))); isprime(n) \\ Charles R Greathouse IV, Sep 26 2012
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CROSSREFS
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Cf. A159236, A069246, A215419-A215421.
Sequence in context: A050674 A164329 A159236 * A249376 A068155 A271367
Adjacent sequences: A215414 A215415 A215416 * A215418 A215419 A215420
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KEYWORD
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nonn,base
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AUTHOR
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Paolo P. Lava, Aug 10 2012
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STATUS
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approved
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