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A191235
Primes p such that the binary representation of p is the concatenation of the binary representations of prime 2 and an odd prime.
2
11, 23, 43, 83, 181, 353, 359, 383, 643, 661, 691, 709, 739, 751, 1301, 1307, 1361, 1373, 1433, 1481, 1487, 1511, 1523, 2617, 2647, 2689, 2707, 2731, 2749, 2767, 2791, 2857, 2887, 3001, 3019, 3061, 3067, 5147, 5189, 5297, 5309, 5333, 5387, 5393
OFFSET
1,1
COMMENTS
The odd primes arising in computing the sequence are 3, 7, 11, 19, 53, 97, 103, 127, 131, 149, 179, 197, 227, 239, ...
Primes whose binary representation equals the binary representation of some prime preceded by 10. - Klaus Brockhaus, May 29 2011
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
11 is in the sequence because 11, 2, 3 in binary are resp. 1011, 10, 11.
83 is in the sequence because 83, 2, 19 in binary are resp. 1010011, 10, 10011.
PROG
(PARI) A053644(n)=my(k=1); while(k<=n, k<<=1); k>>1;
forprime(p=2, 1e3, if(isprime(k=4*A053644(p)+p), print1(k", "))) \\ Charles R Greathouse IV, May 27 2011
(Magma) [ p: p in PrimesInInterval(3, 6100) | exists(q){ k: k in PrimesUpTo(p div 3) | Intseq(p, 2) eq Intseq(k, 2) cat [0, 1] } ]; // Klaus Brockhaus, May 29 2011
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
EXTENSIONS
a(4) corrected, a(15)-a(56) added by Charles R Greathouse IV, May 27 2011
STATUS
approved