A103629 Numbers n such that the string 2357n is the decimal expansion of a prime number.

23, 47, 51, 83, 87, 89, 93, 119, 153, 167, 183, 189, 219, 231, 249, 263, 279, 287, 297, 321, 347, 351, 353, 357, 363, 371, 417, 419, 423, 437, 483, 507, 527, 533, 549, 573, 587, 591, 617, 629, 639, 657, 683, 689, 701, 717, 731, 737, 741, 743, 749, 791, 801

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

23 is in the sequence because 235723 is prime.
89 is in the sequence because 235789 is prime.
167 is in the sequence because 2357167 is prime.

Maple

F:= proc(d) op(select(t -> isprime(2357*10^d+t), [seq(t, t=10^(d-1)+1..10^d-1, 2)])) end proc:
F(2), F(3); # Robert Israel, Jul 15 2018

Mathematica

Select[Range[1000], PrimeQ[FromDigits[Join[{2, 3, 5, 7}, IntegerDigits[ #]]]]&] (* Harvey P. Dale, May 29 2014 *)

Prog

(Magma) [ n: n in [1..900] | IsPrime(Seqint(Intseq(n) cat [7, 5, 3, 2])) ];
(PARI) select(n->isprime(23570*10^logint(n, 10) + n), [1..1000]) \\ Andrew Howroyd, Jul 15 2018

Crossrefs

Sequence in context: A038152 A358684 A344133 * A253177 A109996 A188833

Adjacent sequences: A103626 A103627 A103628 * A103630 A103631 A103632

Keyword

base,nonn

Author

Parthasarathy Nambi, Mar 25 2005

Extensions

More terms from Vincenzo Librandi, Feb 01 2011

Status

approved