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A108106 Numbers n such that the string 1119n is the decimal expansion of a prime number. 1
7, 13, 19, 49, 53, 59, 73, 77, 97, 109, 121, 169, 179, 221, 227, 241, 269, 281, 299, 319, 323, 343, 359, 389, 397, 403, 449, 473, 523, 527, 529, 557, 577, 589, 607, 611, 623, 649, 653, 659, 673, 691, 697, 707, 733, 737, 779, 793, 799, 809, 817, 821, 823 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

11 and 19 are primes.

LINKS

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

EXAMPLE

7 is in the sequence because 11197 is prime.

73 is in the sequence because 111973 is prime.

221 is in the sequence because 1119221 is prime.

MAPLE

a:=proc(n) local z: z:=nops(convert(n, base, 10)): if isprime(1119*10^z+n)=true then n else fi end: seq(a(n), n=1..1000); (Deutsch)

MATHEMATICA

Select[Range[900], PrimeQ[FromDigits[Join[{1, 1, 1, 9}, IntegerDigits[#]]]]&]  (* Harvey P. Dale, May 22 2012 *)

PROG

(MAGMA) [ n: n in [1..900] | IsPrime(Seqint(Intseq(n) cat [9, 1, 1, 1])) ];

CROSSREFS

Cf. A107645, A107644.

Sequence in context: A073648 A298737 A109558 * A231506 A165724 A144232

Adjacent sequences:  A108103 A108104 A108105 * A108107 A108108 A108109

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Jun 25 2005

EXTENSIONS

More terms from Emeric Deutsch, Jul 06 2005

STATUS

approved

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Last modified July 19 22:14 EDT 2019. Contains 325168 sequences. (Running on oeis4.)