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Revision History for A270539

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A270539

Primes p such that gcd(phi(p-1), sigma(p-1)) = 1 with phi = A000010, sigma = A000203.
(history; published version)

#27 by Charles R Greathouse IV at Thu Sep 08 08:46:16 EDT 2022

PROG

(MAGMAMagma) [n: n in [1..10^6] | IsPrime(n) and GCD(SumOfDivisors(n-1), EulerPhi(n-1)) eq 1]

Discussion

Thu Sep 08

08:46

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

#26 by Alois P. Heinz at Wed Oct 06 09:47:27 EDT 2021

STATUS

proposed

approved

#25 by Michel Marcus at Wed Oct 06 09:45:32 EDT 2021

STATUS

editing

proposed

#24 by Michel Marcus at Wed Oct 06 09:45:28 EDT 2021

PROG

(PARI) isok(p) = isprime(p) && (gcd(eulerphi(p-1), sigma(p-1)) == 1); \\ Michel Marcus, Oct 06 2021

#23 by Michel Marcus at Wed Oct 06 09:43:46 EDT 2021

EXAMPLE

Prime 17 is a term because gcd(sigma(16), phi(16)) = gcd(31, 8) = 1.

STATUS

approved

editing

#22 by Bruno Berselli at Thu Aug 01 04:10:00 EDT 2019

STATUS

proposed

approved

#21 by Jon E. Schoenfield at Thu Aug 01 04:08:26 EDT 2019

STATUS

editing

proposed

#20 by Jon E. Schoenfield at Thu Aug 01 04:08:24 EDT 2019

NAME

Primes p such that GCDgcd(phi(p-1), sigma(p-1)) = 1 with phi = A000010, sigma = A000203.

EXAMPLE

Prime 17 is term because GCDgcd(sigma(16), phi(16)) = GCDgcd(31, 8) = 1.

STATUS

approved

editing

#19 by N. J. A. Sloane at Tue Jul 12 22:40:27 EDT 2016

STATUS

proposed

approved

#18 by Jaroslav Krizek at Tue Jul 12 17:20:27 EDT 2016

STATUS

editing

proposed