cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A090707 Primes whose decimal representation is a valid number in base 4 and interpreted as such is again a prime.

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