The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A288939

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A288939

Nonprime numbers k such that k^6 + k^5 + k^4 + k^3 + k^2 + k + 1 is prime.
(history; published version)

#25 by Hugo Pfoertner at Thu Jul 22 23:52:37 EDT 2021

STATUS

proposed

approved

#24 by Jon E. Schoenfield at Thu Jul 22 22:46:08 EDT 2021

STATUS

editing

proposed

#23 by Jon E. Schoenfield at Thu Jul 22 22:46:04 EDT 2021

NAME

Nonprime numbers n k such that nk^6 + nk^5 + nk^4 + nk^3 + nk^2 + n k + 1 is prime.

COMMENTS

The corresponding prime numbers nk^6 + nk^5 + nk^4 + nk^3 + nk^2 + n k + 1 = 1111111_n k are in A194194; all these Brazilian primes belong to A085104 and A285017.

STATUS

approved

editing

#22 by N. J. A. Sloane at Sun Jul 30 12:51:42 EDT 2017

STATUS

reviewed

approved

#21 by Michel Marcus at Sun Jul 30 12:50:41 EDT 2017

STATUS

proposed

reviewed

#20 by Jon E. Schoenfield at Sun Jul 30 12:41:34 EDT 2017

STATUS

editing

proposed

#19 by Jon E. Schoenfield at Sun Jul 30 12:41:30 EDT 2017

COMMENTS

The corresponding prime numbers n^6 + n^5 + n^4 + n^3 + n^2 + n + 1 = (1111111)__n are in A194194; all these Brazilian primes belong to A085104 and A285017.

EXAMPLE

6 is in the sequence because 6^6 + 6^5 + 6^4 + 6^3 + 6^2 + 6 + 1 = (1111111)__6 = 55987 which is prime.

CROSSREFS

Cf. A100330, A053716, A085104, A088550, A194194, A100330, A163268, A194194, A194257, A053716, A085104, A285017.

STATUS

approved

editing

#18 by N. J. A. Sloane at Thu Jul 13 22:24:41 EDT 2017

STATUS

proposed

approved

#17 by Chai Wah Wu at Thu Jul 13 22:10:52 EDT 2017

STATUS

editing

proposed

#16 by Chai Wah Wu at Thu Jul 13 22:10:41 EDT 2017

LINKS

Chai Wah Wu, <a href="/A288939/b288939.txt">Table of n, a(n) for n = 1..10000</a>