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A176838 Primes p such that p^3 = q//3 for a prime q, where "//" denotes concatenation.

%I A176838 #24 Sep 03 2021 13:54:57
%S A176838 17,157,257,277,397,677,877,997,1217,1697,1997,2417,2777,3257,3517,
%T A176838 3697,4157,4177,5077,5197,5897,6277,7417,7517,8377,9397,9497,9677,
%U A176838 9857,11197,11597,12157,12457,12697,13397,13477,13877,14057,14197,15017,16477,17597,18097
%N A176838 Primes p such that p^3 = q//3 for a prime q, where "//" denotes concatenation.
%C A176838 Diophantine equation p^3 = 10 * q + 3 with side condition p and q prime. Necessarily the LSD for such primes p is e = 7 and the two least significant digit strings are "17", "57", "77" or "97".
%D A176838 J.-P. Allouche and J. Shallit, Automatic Sequences, Theory, Applications, Generalizations, Cambridge University Press, 2003.
%D A176838 G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers (Fifth edition), Oxford University Press, 1980.
%D A176838 F. Padberg, Zahlentheorie und Arithmetik, Spektrum Akademie Verlag, Heidelberg - Berlin 1999.
%H A176838 Harvey P. Dale, <a href="/A176838/b176838.txt">Table of n, a(n) for n = 1..1000</a>
%e A176838 17^3 = 4913 = prime(94)//3, 17 = prime(7) is the first term.
%e A176838 157^3 = 3869893 = prime(32838)//3, 157 = prime(37) is the second term.
%p A176838 q:= n-> isprime(iquo(n^3, 10, 'd')) and d=3:
%p A176838 select(q, [ithprime(i)$i=1..3000])[];  # _Alois P. Heinz_, Sep 03 2021
%t A176838 Select[Range[7,20000,10],PrimeQ[#]&&PrimeQ[FromDigits[Most[IntegerDigits[ #^3]]]]&] (* _Harvey P. Dale_, Oct 03 2013 *)
%o A176838 (Python)
%o A176838 from sympy import isprime, primerange
%o A176838 def ok(p): q, r = divmod(p**3, 10); return r == 3 and isprime(q)
%o A176838 print(list(filter(ok, primerange(2, 18200)))) # _Michael S. Branicky_, Aug 31 2021
%o A176838 (PARI) isok(p) = if (isprime(p), my(v=divrem(p^3,10)); isprime(v[1]) && (v[2] == 3)); \\ _Michel Marcus_, Sep 03 2021
%Y A176838 Cf. A000040, A000578, A174979.
%K A176838 base,nonn
%O A176838 1,1
%A A176838 Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 27 2010