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Revision History for A050530

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Showing entries 1-10 | older changes

A050530

Numbers k such that k - phi(k) is prime.
(history; published version)

#20 by Charles R Greathouse IV at Thu Sep 08 08:44:58 EDT 2022

PROG

(MAGMAMagma) [n: n in [1..600] | IsPrime(n-EulerPhi(n))]; // Vincenzo Librandi, Dec 18 2015

Discussion

Thu Sep 08

08:44

OEIS Server: https://oeis.org/edit/global/2944

#19 by Alois P. Heinz at Thu Sep 05 10:41:58 EDT 2019

STATUS

proposed

approved

#18 by Amiram Eldar at Thu Sep 05 10:41:24 EDT 2019

STATUS

editing

proposed

#17 by Amiram Eldar at Thu Sep 05 09:47:31 EDT 2019

LINKS

Amiram Eldar, <a href="/A050530/b050530.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing

#16 by Bruno Berselli at Mon May 28 09:19:47 EDT 2018

STATUS

proposed

approved

#15 by Jon E. Schoenfield at Mon May 28 09:16:09 EDT 2018

STATUS

editing

proposed

#14 by Jon E. Schoenfield at Mon May 28 09:16:07 EDT 2018

NAME

Numbers n k such that n k - phi(nk) is prime.

COMMENTS

If nk = p^2 is the square of a prime, then p^2 - phi(p^2) = p, so this sequence is infinite and generates all primes.

No p prime belongs here p is a term of this sequence because A051953(p)=1. Other cases exist, ; e.g. n, k - phi(nk) = 23 if nk = 95, 119, 143, 529.

FORMULA

Numbers n k such that A051953(nk) is prime.

STATUS

approved

editing

#13 by Bruno Berselli at Fri Dec 18 03:33:19 EST 2015

STATUS

proposed

approved

#12 by Vincenzo Librandi at Fri Dec 18 03:29:30 EST 2015

STATUS

editing

proposed

Discussion

Fri Dec 18

03:33

Bruno Berselli: Stop, Vincenzo. Thanks!

#11 by Vincenzo Librandi at Fri Dec 18 03:29:23 EST 2015

PROG

(MAGMA) [n: n in [1..600] | IsPrime(n-EulerPhi(n))]; // Vincenzo Librandi, Dec 18 2015

STATUS

approved

editing