%I #15 Jan 27 2017 13:13:37
%S 3,23,41,47,59,89,101,149,179,227,317,347,353,383,389,479,503,599,821,
%T 887,929,977,1019,1109,1229,1283,1319,1511,1571,1619,1667,1709,1733,
%U 1787,1847,1889,1907,1913,1931,2207,2309,2333,2357,2399,2417,2459,2609,2753,2789,2909,2963,2999,3203,3257,3299
%N Prime numbers p such that the decimal representation of its Elias gamma code is also a prime.
%H Indranil Ghosh, <a href="/A281551/b281551.txt">Table of n, a(n) for n = 1..2014</a>
%e 59 is in the sequence because the decimal representation of its Elias gamma code is 2011 and both 59 and 2011 are prime numbers.
%o (Python)
%o import math
%o from sympy import isprime
%o def unary(n):
%o ....return "1"*(n-1)+"0"
%o def elias_gamma(n):
%o ....if n ==1:
%o ........return "1"
%o ....k=int(math.log(n,2))
%o ....fp=unary(1+k) #fp is the first part
%o ....sp=n-2**(k) #sp is the second part
%o ....nb=k #nb is the number of bits used to store sp in binary
%o ....sp=bin(sp)[2:]
%o ....if len(sp)<nb:
%o ........sp=("0"*(nb-len(sp)))+sp
%o ....return int(fp+sp,2)
%o i=1
%o j=1
%o while j<=2014:
%o ....if isprime(i)==True and isprime(elias_gamma(i))==True:
%o ........print str(j)+" "+str(i)
%o ........j+=1
%o ....i+=1
%Y Cf. A000040, A171885 (decimal representation of Elias gamma code), A281149, A281316.
%K nonn,base
%O 1,1
%A _Indranil Ghosh_, Jan 24 2017