A185949 - OEIS

%I #13 May 20 2021 12:46:28

%S 11,101,21001,1810001,2100001,61000001,2010000001,11100000001,

%T 61000000001,1810000000001,14100000000001,151000000000001,

%U 5010000000000001,9100000000000001,271000000000000001,1110000000000000001,24100000000000000001,261000000000000000001,3910000000000000000001,11100000000000000000001

%N Smallest prime ending in 10^n+1 in its base-10 representation.

%H Robert Israel, <a href="/A185949/b185949.txt">Table of n, a(n) for n = 1..995</a>

%p f:= proc(n) local p;

%p   for p from 10^n+1 by 10^(n+1) do

%p     if isprime(p) then return p fi

%p   od

%p end proc:

%p map(f, [$1..30]); # _Robert Israel_, May 03 2018

%t Table[k=0; While[!PrimeQ[p=FromDigits[Join[IntegerDigits[k], IntegerDigits[10^n+1]]]], k++]; p, {n,20}]

%o (Python)

%o from sympy import isprime as is_prime

%o # This implementation assumes function is_prime(n)

%o # returns True if n is prime, or False otherwise:

%o for n in range (1, 100):

%o     pattern = 10**n + 1

%o     for j in range (0, 10000000):

%o         if (j == 0):

%o             num = "%d" % (pattern)

%o         else:

%o             num = "%d%d" % (j, pattern)

%o         if (is_prime(num)):

%o             print(num)

%o             break

%K nonn,base

%O 1,1

%A _Amir H. Farrahi_, Feb 07 2011