A108107 - OEIS

A108107

Numbers n such that the string 1123n is the decimal expansion of a prime number.

9, 27, 31, 37, 39, 49, 61, 63, 97, 127, 151, 181, 189, 211, 217, 219, 231, 247, 267, 279, 303, 307, 319, 327, 349, 351, 361, 379, 391, 399, 403, 427, 429, 439, 477, 483, 487, 501, 511, 517, 531, 541, 553, 561, 567, 589, 597, 601, 621, 631, 637, 651, 667

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OFFSET

1,1

COMMENTS

11 and 23 are primes.

LINKS

Table of n, a(n) for n=1..53.

EXAMPLE

9 is in the sequence because 11239 is prime.

63 is in the sequence because 112363 is prime.

127 is in the sequence because 1123127 is prime.

MAPLE

a:=proc(n) local z: z:=nops(convert(n, base, 10)): if isprime(1123*10^z+n)=true then n else fi end: seq(a(n), n=1..750); # Emeric Deutsch, Jul 02 2005

PROG

(Magma) [ n: n in [1..700] | IsPrime(Seqint(Intseq(n) cat [3, 2, 1, 1])) ];

CROSSREFS

Cf. A107645, A107644.

Sequence in context: A022701 A276003 A255343 * A340237 A216168 A036303

Adjacent sequences: A108104 A108105 A108106 * A108108 A108109 A108110

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Jun 25 2005

EXTENSIONS

More terms from Emeric Deutsch, Jul 02 2005

STATUS

approved