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A050674 Inserting a digit '0' between adjacent digits of n makes a prime. 22
11, 13, 17, 19, 37, 41, 49, 53, 59, 61, 67, 71, 79, 89, 97, 107, 109, 113, 131, 133, 151, 161, 167, 179, 193, 199, 211, 217, 221, 247, 257, 259, 277, 287, 289, 293, 313, 319, 323, 337, 343, 359, 373, 377, 383, 389, 409, 457, 469, 479, 481, 493, 511, 527, 553 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

373 becomes 3(0)7(0)3 which is prime 30703.

MATHEMATICA

(* This program works in Mathematica 6.0 and later *)

Select[Range[11, 1000, 2], PrimeQ[FromDigits[Riffle[IntegerDigits[#], 0]]] &] (* T. D. Noe, Dec 22 2010 *)

(* The following program has been tested in Mathematica 5.1 and it works *)

Reap[c = 0; d = 0; Do[If[MemberQ[{1, 3, 7, 9}, Mod[n, 10]], id = IntegerDigits[n]; Do[id[[k]] = {id[[k]], d}, {k, Length[id] - 1}]; If[PrimeQ[FromDigits[Flatten[id]]], Sow[n]; c++; If[c > 999, Break[]]]], {n, 11, 20000}]][[2, 1]] (* Zak Seidov, Dec 22 2010 *)

CROSSREFS

Cf. A050711, A050712, A050713, A050715, A050716, A050717, A050718, A050719.

Sequence in context: A181576 A076162 A156902 * A164329 A159236 A215417

Adjacent sequences:  A050671 A050672 A050673 * A050675 A050676 A050677

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Aug 15 1999

EXTENSIONS

Offset set to 1 by Georg Fischer, Oct 15 2019

STATUS

approved

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Last modified November 13 07:13 EST 2019. Contains 329085 sequences. (Running on oeis4.)