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%I #34 Sep 06 2021 16:48:00
%S 2,3,11,13,23,31,101,103,113,131,211,223,233,311,331,1013,1021,1033,
%T 1103,1201,1213,1223,1231,1301,2003,2111,2113,2131,2203,2213,2311,
%U 2333,3001,3011,3203,3221,3301,3323,10111,10211,10303,10313,10321,10331
%N Primes whose decimal representation is a valid number in base 4 and interpreted as such is again a prime.
%H Charles R Greathouse IV, <a href="/A090707/b090707.txt">Table of n, a(n) for n = 1..10000</a>
%H Alejandro J. Becerra Jr., <a href="https://github.com/ajbecerr/OEIS/blob/main/A089971%2C%20A089981%2C%20A090707-A090710%2C%20A235394-A235395.ipynb">Python code for computing terms of A089971, A089981, A090707-A090710, A235394-A235395</a>.
%e 13 is prime in decimal and also when considered as a number in base 4: 13 [base 4] = 7 [base 10] which is also prime.
%t Select[ FromDigits@# & /@ IntegerDigits[ Prime@ Range@ 270, 4], PrimeQ] (* _Robert G. Wilson v_, Jan 05 2014 *)
%t FromDigits[#,10]&/@Select[Tuples[{0,1,2,3},5],AllTrue[{FromDigits[#,4],FromDigits[#,10]},PrimeQ]&] (* _Harvey P. Dale_, Jul 30 2021 *)
%o (PARI) forprime(p=2,1e4, if(isprime(t=fromdigits(digits(p,4))), print1(t", "))) \\ _Charles R Greathouse IV_, Apr 22 2015
%Y Cf. A031974, A089971, A089981, A090708, A090709, A090710, A235394, A235395, A000040.
%K base,nonn
%O 1,1
%A _Cino Hilliard_, Jan 18 2004
%E Name, example and offset corrected by _M. F. Hasler_, Jan 03 2014
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