|
%I #22 May 29 2022 08:08:24
%S 2,5,149,401,509,773,809,1021,1103,1289,1301,1451,1697,1709,1747,1877,
%T 1889,2087,2389,2521,2663,3373,3511,3631,3733,3779,3821,3919,3947,
%U 3989,4003,4073,4241,4289,4339,4637,4643,4801,4931,5039,5113,5387,5417,5477
%N Prime numbers p such that prepending any single decimal digit to p does not produce a prime.
%C 149 is in the sequence, because the following numbers are all composite: 1149, 2149, 3149, 4149, 5149, 6149, 7149, 8149 and 9149.
%H Michael S. Branicky, <a href="/A155762/b155762.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Prime@Range@1000, NoneTrue[#+10^IntegerLength@#*Range@9, PrimeQ]&] (* _Hans Rudolf Widmer_, May 28 2022 *)
%o (Python)
%o from sympy import isprime, primerange
%o def ok(p): return not any(isprime(int(d+str(p))) for d in "123456789")
%o print(list(filter(isprime, primerange(2, 5500)))) # _Michael S. Branicky_, May 28 2022
%Y Cf. A119289.
%K nonn,base
%O 1,1
%A _Dmitry Kamenetsky_, Jan 26 2009
|
