login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A103629 Numbers n such that the string 2357n is the decimal expansion of a prime number. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A008605 A038152 A130604 * 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 26 13:59 EST 2021. Contains 341632 sequences. (Running on oeis4.)