The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A235395 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A235395

Primes whose decimal representation is a valid number in base 9 and interpreted as such is again a prime.
(history; published version)

#12 by Charles R Greathouse IV at Mon Nov 07 12:36:48 EST 2016

STATUS

editing

approved

#11 by Charles R Greathouse IV at Mon Nov 07 12:36:45 EST 2016

PROG

list(lim)=my(v=List(), t); forprime(p=2, fixBase(lim\1, 10, 89), if(isprime(t=fromdigits(digits(p, 9), 10)), listput(v, t))); Vec(v) \\ Charles R Greathouse IV, Nov 07 2016

STATUS

approved

editing

#10 by Charles R Greathouse IV at Mon Nov 07 12:34:12 EST 2016

STATUS

editing

approved

#9 by Charles R Greathouse IV at Mon Nov 07 12:34:09 EST 2016

LINKS

Charles R Greathouse IV, <a href="/A235395/b235395.txt">Table of n, a(n) for n = 1..10000</a>

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, 9), 10)), listput(v, t))); Vec(v) \\ Charles R Greathouse IV, Nov 07 2016

STATUS

approved

editing

#8 by N. J. A. Sloane at Fri Jan 17 18:27:29 EST 2014

STATUS

proposed

approved

#7 by Robert G. Wilson v at Fri Jan 17 15:45:17 EST 2014

STATUS

editing

proposed

#6 by M. F. Hasler at Mon Jan 13 23:16:09 EST 2014

LINKS

M. F. Hasler, <a href="https://docs.google.com/document/d/10IM7fcAbB2tqRGuwfGvuEGUzD_IXbgXPDK0tfxN4M3o/pub">Primes whose base c expansion is also the base b expansion of a prime</a>

CROSSREFS

Cf. A065727, A031974, A089971, A089981, A090707, A090708, A090709, A090710, A235394, A000040.

STATUS

proposed

editing

#5 by Robert G. Wilson v at Sun Jan 12 22:33:03 EST 2014

STATUS

editing

proposed

#4 by Robert G. Wilson v at Sun Jan 12 22:33:01 EST 2014

NAME

Primes whose decimal representation is a valid number in base 9 and interpreted as such is again a prime.

MATHEMATICA

Select[FromDigits@# & /@ IntegerDigits[ Prime@ Range@ 270, 9], PrimeQ]

CROSSREFS

Cf. A031974, A089971, A089981, A090707, A090708, A090709, A090710, A235394, A000040.

KEYWORD

nonn,base,easy,changednonn

STATUS

proposed

editing

#3 by Robert G. Wilson v at Thu Jan 09 19:11:36 EST 2014

STATUS

editing

proposed

Discussion

Sat Jan 11

04:51

Joerg Arndt: "base"