The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A068677 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A068677

Numbers that yield a prime when a 7 is prefixed or suffixed to them.
(history; published version)

#15 by Joerg Arndt at Fri Aug 23 03:03:19 EDT 2024

STATUS

reviewed

approved

#14 by Stefano Spezia at Fri Aug 23 02:30:55 EDT 2024

STATUS

proposed

reviewed

#13 by Michel Marcus at Thu Aug 22 12:36:38 EDT 2024

STATUS

editing

proposed

#12 by Michel Marcus at Thu Aug 22 12:36:35 EDT 2024

MATHEMATICA

Flatten@Position[{# +7*10^IntegerLength@#, 7+10*#}&/@Range@10000, {_?PrimeQ ..}] (* _Hans Rudolf Widmer_, Aug 22 2024 *)

(* Hans Rudolf Widmer, Aug 22 2024 *)

STATUS

proposed

editing

#11 by Hans Rudolf Widmer at Thu Aug 22 12:19:13 EDT 2024

STATUS

editing

proposed

#10 by Hans Rudolf Widmer at Thu Aug 22 12:18:32 EDT 2024

MATHEMATICA

Flatten@Position[{# +7*10^IntegerLength@#, 7+10*#}&/@Range@10000, {_?PrimeQ ..}]

(* Hans Rudolf Widmer, Aug 22 2024 *)

STATUS

approved

editing

#9 by Susanna Cuyler at Sun May 06 00:42:57 EDT 2018

STATUS

proposed

approved

#8 by Jon E. Schoenfield at Sun May 06 00:27:45 EDT 2018

STATUS

editing

proposed

#7 by Jon E. Schoenfield at Sun May 06 00:27:43 EDT 2018

NAME

Number which yields Numbers that yield a prime when a 7 is prefixed or suffixed to itthem.

EXAMPLE

129 belongs to this sequence as both 1297 as well as and 7129 both are primes.

STATUS

approved

editing

#6 by N. J. A. Sloane at Thu Dec 05 19:55:12 EST 2013

AUTHOR

_Amarnath Murthy (amarnath_murthy(AT)yahoo.com), _, Mar 02 2002

Discussion

Thu Dec 05

19:55

OEIS Server: https://oeis.org/edit/global/2075