The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A235465 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A235465

Primes whose base-8 representation also is the base-2 representation of a prime.
(history; published version)

#12 by Joerg Arndt at Wed Apr 14 01:17:15 EDT 2021

STATUS

reviewed

approved

#11 by Michel Marcus at Wed Apr 14 00:22:03 EDT 2021

STATUS

proposed

reviewed

#10 by Jon E. Schoenfield at Wed Apr 14 00:21:34 EDT 2021

STATUS

editing

proposed

#9 by Jon E. Schoenfield at Wed Apr 14 00:21:32 EDT 2021

NAME

Primes whose base -8 representation also is the base -2 representation of a prime.

COMMENTS

This sequence is part of the two -dimensional array of sequences based on this same idea for any two different bases b, c > 1. Sequence A235265 and A235266 are the most elementary ones in this list. Sequences A089971, A089981 and A090707 through A090721, and sequences A065720 - A065727, follow the same idea with one base equal to 10.

EXAMPLE

E.g., 73 = 111[_8] and 111[_2] = 7 are both are prime, so 73 is a term.

STATUS

approved

editing

#8 by Alois P. Heinz at Mon Mar 12 17:20:16 EDT 2018

STATUS

editing

approved

#7 by Alois P. Heinz at Mon Mar 12 17:20:13 EDT 2018

LINKS

Alois P. Heinz, <a href="/A235465/b235465.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing

#6 by M. F. Hasler at Mon Jan 13 23:12:24 EST 2014

STATUS

editing

approved

#5 by M. F. Hasler at Mon Jan 13 23:12:13 EST 2014

CROSSREFS

Cf. A235478, A235479, A065720 ⊂ A036952, A065721 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235461 - A235482. See the LINK for further cross-references.

#4 by M. F. Hasler at Sun Jan 12 16:51:02 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. A065720 ⊂ A036952, A065721 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235461 - A235482. See the LINK for further cross-references.

#3 by M. F. Hasler at Sat Jan 11 15:28:03 EST 2014

PROG

(PARI) forprime(p=1, 1e3, is(p, 8, 2)&&print1(vector(#d=digits(p, 2), i, 8^(#d-i))*d~, ", ")) \\ To produce the terms, this is much more efficient than to select them using straightforwardly is(.)=is(., 2, 78)