A105435 Primes which with a 1 prepended remain prime.

3, 7, 13, 31, 37, 67, 73, 79, 97, 103, 109, 151, 163, 181, 193, 223, 229, 277, 283, 307, 367, 373, 409, 433, 439, 487, 499, 523, 571, 601, 607, 613, 619, 709, 733, 787, 811, 823, 877, 907, 997, 1069, 1087, 1093, 1117, 1171, 1213, 1279, 1321, 1399, 1423, 1447

Offset

1,1

Links

T. D. Noe, Table of n, a(n) for n = 1..10000

Maple

with(numtheory); for i from 1 to 500 do if isprime(10^(ceil(log[10](ithprime(i))))+ithprime(i)) then printf(`%d, `, ithprime(i)) fi: od: # James A. Sellers, Apr 09 2005

Mathematica

Select[ Prime[ Range[ 230]], PrimeQ[ FromDigits[ Join[{1}, IntegerDigits[ # ]]]] &] (* Robert G. Wilson v, Apr 09 2005 *)
Select[Prime[Range[250]], PrimeQ[10^IntegerLength[#]+#]&] (* Harvey P. Dale, May 30 2023 *)

Crossrefs

Cf. A023237.

Sequence in context: A049488 A136051 A100750 * A117708 A093431 A243765

Adjacent sequences: A105432 A105433 A105434 * A105436 A105437 A105438

Keyword

nonn,base

Author

Lekraj Beedassy, Apr 08 2005

Extensions

Corrected and extended by Robert G. Wilson v and James A. Sellers, Apr 09 2005

Status

approved