The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A060800

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A060800

a(n) = p^2 + p + 1 where p runs through the primes.
(history; published version)

#56 by Michael De Vlieger at Mon Nov 07 07:39:34 EST 2022

STATUS

reviewed

approved

#55 by Joerg Arndt at Mon Nov 07 03:34:21 EST 2022

STATUS

proposed

reviewed

#54 by Amiram Eldar at Mon Nov 07 03:14:13 EST 2022

STATUS

editing

proposed

#53 by Amiram Eldar at Mon Nov 07 02:57:39 EST 2022

LINKS

R. J. Mathar, <a href="/A060800/a060800.pdf">No common terms in the sequences sigma(p^i) and sigma(p^(i+1)) as p runs through the primes</a>.

FORMULA

Product_{n>=1} (1 - 1/a(n)) = zeta(3)/zeta(2) (A253905). - Amiram Eldar, Nov 07 2022

EXAMPLE

a(3) = 31 because 5^2 + 5 + 1 = 31.

CROSSREFS

Cf. A001248, A131991, A131992, A131993, A253905.

STATUS

approved

editing

#52 by Charles R Greathouse IV at Thu Sep 08 08:45:03 EDT 2022

PROG

(MAGMAMagma) [p^2+p+1: p in PrimesUpTo(200)]; // Vincenzo Librandi, Mar 20 2014

Discussion

Thu Sep 08

08:45

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

#51 by R. J. Mathar at Fri Aug 05 07:27:15 EDT 2022

STATUS

editing

approved

#50 by R. J. Mathar at Fri Aug 05 07:27:07 EDT 2022

LINKS

R. J. Mathar, <a href="http://www.mpia.de/~mathar/publicA060800/mathar20180318a060800.pdf">No common terms in the sequences sigma(p^i) and sigma(p^(i+1)) as p runs through the primes</a>, 2018.

STATUS

approved

editing

#49 by R. J. Mathar at Mon Mar 19 03:42:15 EDT 2018

STATUS

editing

approved

#48 by R. J. Mathar at Mon Mar 19 03:42:08 EDT 2018

LINKS

R. J. Mathar, <a href="http://www.mpia.de/~mathar/public/mathar20180317mathar20180318.pdf">No common terms in the sequences sigma(p^i) and sigma(p^(i+1)) as p runs through the primes</a>, 2018.

STATUS

approved

editing

#47 by Joerg Arndt at Sun Mar 18 04:39:18 EDT 2018

STATUS

proposed

approved