OFFSET
1,1
COMMENTS
In general rebase notation (Marc LeBrun): p8 = (8) [p] (10).
LINKS
Harry J. Smith, Table of n, a(n) for n = 1..1000
EXAMPLE
E.g., 787_10 = 1423_8 is prime, and so is 1423_10.
MATHEMATICA
Select[ Range[2500], PrimeQ[ # ] && PrimeQ[ FromDigits[ IntegerDigits[ #, 8]]] & ]
PROG
(PARI) baseE(x, b)= { local(d, e=0, f=1); while (x>0, d=x-b*(x\b); x\=b; e+=d*f; f*=10); return(e) } { n=0; for (m=1, 10^9, p=prime(m); b=baseE(p, 8); if (isprime(b), write("b065726.txt", n++, " ", p); if (n==1000, return)) ) } \\ Harry J. Smith, Oct 28 2009
(PARI) is(p, b=10, c=8)=isprime(vector(#d=digits(p, c), i, b^(#d-i))*d~)&&isprime(p) \\ This code can be used for other bases b, c when b>c. See A235265 for code also valid for b<c. \\ M. F. Hasler, Jan 12 2014
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Nov 15 2001
EXTENSIONS
Definition clarified by M. F. Hasler, Jan 12 2014
STATUS
approved