A091923 Primes whose decimal representations interpreted in base 11 are not prime.
11, 13, 17, 19, 23, 31, 37, 41, 47, 53, 59, 71, 73, 79, 83, 97, 101, 103, 107, 109, 113, 127, 131, 137, 149, 151, 157, 163, 167, 173, 179, 181, 191, 211, 223, 229, 233, 239, 241, 251, 257, 271, 277, 283, 293, 307, 311, 313, 317, 337, 347, 349, 359, 367, 383
Offset: 1
Examples
A000040(9)=23 in base 11 is 2*11^1 + 3*11^0 = 25 = 5^2, therefore 29 is a term.
Links
- Marius A. Burtea, Table of n, a(n) for n = 1..1045
Crossrefs
Cf. A091924.
Programs
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Magma
[n:n in PrimesUpTo(400)| not IsPrime(Seqint(Intseq(n), 11))]; // Marius A. Burtea, Jun 30 2019
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Mathematica
Select[Prime@Range@80, ! PrimeQ@FromDigits[IntegerDigits@#, 11] &] (* Vincenzo Librandi, Jul 01 2019 *)
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PARI
isok(p) = isprime(p) && (d=digits(p)) && !isprime(fromdigits(d, 11)); \\ Michel Marcus, Jun 30 2019
Extensions
Corrected by Zak Seidov, Feb 25 2004
Comments