A103603 Numbers k such that the string 101001000k is prime.

7, 29, 41, 79, 119, 137, 143, 169, 187, 241, 259, 263, 281, 307, 313, 319, 341, 361, 377, 403, 427, 439, 449, 461, 467, 493, 547, 553, 557, 587, 673, 689, 701, 703, 719, 721, 731, 781, 791, 847, 887, 901, 911, 931, 943, 979, 1027, 1073, 1093, 1097, 1103, 1207, 1219, 1229, 1307, 1327, 1331

Offset

1,1

Links

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Example

If k=7, then 101001000k = 1010010007 (prime).
If k=41, then 101001000k = 10100100041 (prime).
If k=119, then 101001000k = 101001000119 (prime).

Mathematica

Select[Range[1500], PrimeQ[FromDigits[Join[{1, 0, 1, 0, 0, 1, 0, 0, 0}, IntegerDigits[ #]]]]&] (* Harvey P. Dale, Jul 12 2011 *)
Select[Range[2000], PrimeQ[101001000*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Jan 16 2020 *)

Prog

(Magma) [ n: n in [1..1750] | IsPrime(Seqint(Intseq(n) cat [0, 0, 0, 1, 0, 0, 1, 0, 1])) ]; // Vincenzo Librandi, Feb 02 2011

Crossrefs

Sequence in context: A155476 A166970 A075583 * A045465 A330723 A165492

Adjacent sequences: A103600 A103601 A103602 * A103604 A103605 A103606

Keyword

base,nonn

Author

Parthasarathy Nambi, Mar 23 2005

Status

approved