The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A154967 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A154967

Nonprime numbers n such that concatenation of n and n-th prime is composite.
(history; published version)

#13 by Charles R Greathouse IV at Thu Sep 08 08:45:40 EDT 2022

PROG

(MAGMAMagma) [ n: n in [1..118] | not IsPrime(n) and not IsPrime(StringToInteger(IntegerToString(n) cat IntegerToString(NthPrime(n)))) ];

Discussion

Thu Sep 08

08:45

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

#12 by Michel Marcus at Sat May 12 05:25:13 EDT 2018

STATUS

reviewed

approved

#11 by Joerg Arndt at Sat May 12 02:25:17 EDT 2018

STATUS

proposed

reviewed

#10 by Michel Marcus at Sat May 12 01:07:51 EDT 2018

STATUS

editing

proposed

#9 by Michel Marcus at Sat May 12 01:07:48 EDT 2018

EXAMPLE

The concatenation of the nonprime 1 and the first prime 2 is the composite 12, hence 1 is in the sequence. Concatenation of nonprime 9 and ninth prime 23 is the composite 923 = 13*71, hence 9 is in the sequence.

Concatenation of nonprime 9 and ninth prime 23 is the composite 923 = 13*71, hence 9 is in the sequence.

STATUS

proposed

editing

#8 by Jon E. Schoenfield at Sat May 12 00:41:14 EDT 2018

STATUS

editing

proposed

#7 by Jon E. Schoenfield at Sat May 12 00:41:12 EDT 2018

EXTENSIONS

Edited and extended beyond a(12) by _Klaus Brockhaus, _, Jan 20 2009

STATUS

approved

editing

#6 by Harvey P. Dale at Thu Mar 08 17:01:32 EST 2018

STATUS

editing

approved

#5 by Harvey P. Dale at Thu Mar 08 17:01:28 EST 2018

LINKS

Harvey P. Dale, <a href="/A154967/b154967.txt">Table of n, a(n) for n = 1..1000</a>

STATUS

approved

editing

#4 by Harvey P. Dale at Thu Mar 08 17:00:15 EST 2018

STATUS

editing

approved