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A053547 Smallest prime starting with A000422(n).

%I A053547 #17 Apr 01 2020 12:13:32
%S A053547 11,211,3217,432121,543217,65432117,76543217,876543211,9876543211,
%T A053547 1098765432101,11109876543211,12111098765432101,1312111098765432139,
%U A053547 141312111098765432113,15141312111098765432173
%N A053547 Smallest prime starting with A000422(n).
%H A053547 Chai Wah Wu, <a href="/A053547/b053547.txt">Table of n, a(n) for n = 1..100</a>
%e A053547 a(6)=65432117 is smallest prime beginning with the string 654321.
%t A053547 Flatten[Select[Join[10 #+Range[1,9,2],100 #+Range[1,99,2]],PrimeQ,1]&/@ Table[FromDigits[Flatten[IntegerDigits/@Range[n,1,-1]]],{n,25}]] (* _Harvey P. Dale_, Nov 04 2011 *)
%o A053547 (Python)
%o A053547 from sympy import isprime
%o A053547 def A053547(n):
%o A053547     s = int(''.join(str(m) for m in range(n,0,-1)))
%o A053547     for i in range(1,10):
%o A053547         s *= 10
%o A053547         for j in range(1,10**i,2):
%o A053547             x = s+j
%o A053547             if isprime(x):
%o A053547                 return x
%o A053547     else:
%o A053547         return 'search limit reached.' # _Chai Wah Wu_, Jan 02 2015
%Y A053547 Cf. A000422.
%K A053547 easy,nice,nonn,base
%O A053547 1,1
%A A053547 _Enoch Haga_, Jan 16 2000