This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A235394 Primes whose decimal representation is a valid number in base 8 and interpreted as such is again a prime. 68
 2, 3, 5, 7, 13, 23, 37, 53, 73, 103, 107, 131, 211, 227, 263, 277, 307, 337, 373, 401, 431, 433, 463, 467, 521, 541, 547, 557, 577, 631, 643, 661, 673, 701, 1013, 1063, 1151, 1153, 1201, 1223, 1327, 1423, 1451, 1453, 1531, 1567, 1613, 1627, 1663, 1721, 2011, 2017 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 EXAMPLE a(5) = 13_10 = prime(5), 13_8 = 3 + 1*8 = 11_10 = prime(4). a(8) = 53_10 = prime(16), 53_8 = 3 + 5*8 = 43_10 = prime(14). - Marius A. Burtea, Jun 30 2019 MATHEMATICA Select[FromDigits@# & /@ IntegerDigits[ Prime@ Range@ 270, 8], PrimeQ] PROG (PARI) fixBase(n, oldBase, newBase)=my(d=digits(n, oldBase), t=newBase-1); for(i=1, #d, if(d[i]>t, for(j=i, #d, d[j]=t); break)); fromdigits(d, newBase) list(lim)=my(v=List(), t); forprime(p=2, fixBase(lim\1, 10, 8), if(isprime(t=fromdigits(digits(p, 8), 10)), listput(v, t))); Vec(v) \\ Charles R Greathouse IV, Nov 07 2016 (MAGMA)  [n:n in PrimesUpTo(2100)| Max(Intseq(n, 10)) le 7 and IsPrime(Seqint(Intseq(Seqint(Intseq(n), 8))))]; // Marius A. Burtea, Jun 30 2019 CROSSREFS Cf. A031974, A089971, A089981, A090707, A090708, A090709, A090710, A235395, A000040. Sequence in context: A211073 A182315 A233862 * A126092 A132394 A295262 Adjacent sequences:  A235391 A235392 A235393 * A235395 A235396 A235397 KEYWORD base,easy,nonn AUTHOR Robert G. Wilson v, Jan 09 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 12 22:06 EST 2019. Contains 329963 sequences. (Running on oeis4.)