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%I #19 Nov 25 2015 21:07:20
%S 3,11,371,1123,8203,11899,16019
%N Numbers n such that the concatenation of the first n digits of the digital expansion of 1/137 is prime.
%C No further terms through 5000.
%C a(n) == 3 mod 8 for all n. If m <> 3 mod 8, then the concatenation of the first m digits is either even or a multiple of 3. - _Chai Wah Wu_, Nov 24 2015
%D Clifford A. Pickover, A Passion for Mathematics, John Wiley & Sons, Inc., 2005, p. 88.
%t Select[Range[2000],PrimeQ[FromDigits[PadRight[{},#,{0,0,7,2,9,9,2,7}]]]&]
%o (Python)
%o from sympy import isprime
%o A264725_list,c,n,m,k = [],3,7,29927007,10**8
%o for i in range(1,50):
%o if isprime(n):
%o A264725_list.append(c)
%o c += 8
%o n = n*k+m # _Chai Wah Wu_, Nov 24 2015
%K nonn,base,more
%O 1,1
%A _Harvey P. Dale_, Nov 22 2015
%E a(5)-a(7) from _Chai Wah Wu_, Nov 24 2015
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