The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A231235 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A231235

Primes q of the form p^2 + 4 (p prime) such that r = q^2 + 4, s = r^2 + 4 and t = s^2 + 4 are all prime.
(history; published version)

#20 by Harvey P. Dale at Sun Jun 06 15:22:24 EDT 2021

STATUS

editing

approved

#19 by Harvey P. Dale at Sun Jun 06 15:22:01 EDT 2021

MATHEMATICA

extnd[p_]:=NestList[#^2+4&, p, 4]; #^2+4&/@Select[Prime[ Range[ 452*10^6]], AllTrue[ Rest[extnd[#], ], PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 06 2021 *)

STATUS

approved

editing

#18 by Harvey P. Dale at Sun Jun 06 15:06:32 EDT 2021

STATUS

editing

approved

#17 by Harvey P. Dale at Sun Jun 06 15:06:29 EDT 2021

MATHEMATICA

extnd[p_]:=NestList[#^2+4&, p, 4]; #^2+4&/@Select[Prime[ Range[ 452*10^6]], AllTrue[ extnd[#], PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 06 2021 *)

STATUS

approved

editing

#16 by Harvey P. Dale at Sun Jun 06 14:59:57 EDT 2021

STATUS

editing

approved

#15 by Harvey P. Dale at Sun Jun 06 14:59:53 EDT 2021

NAME

Primes q of the form p^2 + 4 (p prime) such that r = q^2 + 4, s = r^2 + 4 and t = rs^2 + 4 are all prime.

EXTENSIONS

Definition corrected by Harvey P. Dale, Jun 06 2021

STATUS

approved

editing

#14 by OEIS Server at Thu Nov 07 23:20:07 EST 2013

LINKS

Zak Seidov and Charles R Greathouse IV, <a href="/A231235/b231235_1.txt">Table of n, a(n) for n = 1..250</a> (first 100 terms from Zak Seidov)

#13 by T. D. Noe at Thu Nov 07 23:20:07 EST 2013

STATUS

editing

approved

Discussion

Thu Nov 07

23:20

OEIS Server: Installed new b-file as b231235.txt.  Old b-file is now b231235_1.txt.

#12 by T. D. Noe at Thu Nov 07 23:20:04 EST 2013

COMMENTS

"Next The next iteration" is impossible: t^2 + 4 is divisible by 13.

LINKS

Zak Seidov and Charles R Greathouse IV, <a href="/A231235/b231235_1.txt">Table of n, a(n) for n = 1..250</a> (first 100 terms from Zak Seidov)

STATUS

proposed

editing

#11 by Zak Seidov at Thu Nov 07 07:03:49 EST 2013

STATUS

editing

proposed