A107073 Numbers n such that the string 35n is prime.

3, 9, 11, 17, 27, 29, 33, 39, 41, 47, 57, 59, 71, 81, 83, 93, 107, 111, 117, 129, 141, 149, 153, 159, 171, 201, 221, 227, 251, 257, 267, 279, 281, 291, 311, 317, 323, 327, 339, 353, 363, 381, 393, 401, 407, 419, 423, 437, 447, 449, 461, 491, 507, 509, 521, 527

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Example

If n=47 then 3547 is prime.

Maple

A055642 := proc(n) max(1, ilog10(n)+1) ; end: cat2 := proc(a, b) a*10^A055642(b)+b ; end: for n from 1 to 1000 do if isprime( cat2(35, n) ) then printf("%d, ", n) ; fi; od: # R. J. Mathar, Jan 16 2009

Mathematica

Select[Range[600], PrimeQ[FromDigits[Join[{3, 5}, IntegerDigits[#]]]]&] (* Harvey P. Dale, Jun 06 2015 *)

Prog

(Magma) [ n: n in [1..900] | IsPrime(Seqint(Intseq(n) cat [5, 3])) ]; // Vincenzo Librandi, Feb 03 2011

Crossrefs

Cf. A032666. - R. J. Mathar, Jan 16 2009

Sequence in context: A050538 A062227 A111324 * A227245 A173394 A111211

Adjacent sequences: A107070 A107071 A107072 * A107074 A107075 A107076

Keyword

nonn,base

Author

Parthasarathy Nambi, Jun 07 2005

Status

approved