login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A034818 Concatenations C1 and C2 and C3 are all prime (see the comment lines). 0
657, 4929, 10647, 18291, 20907, 22653, 27381, 28053, 28671, 42471, 48441, 57363, 69651, 79569, 89853, 93261, 95967, 101283, 110763, 119481, 128613, 145719, 149409, 174993, 201417, 204861, 205329, 221883, 248391, 269199, 272799, 293451 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

C1 = 'nextprime(n) followed by n'

C2 = 'n followed by prevprime(n)'

C3 = 'nextprime(n) followed by n followed by prevprime(n)'

LINKS

Table of n, a(n) for n=0..31.

EXAMPLE

n=95967 -> next prime is 95971, previous prime is 95959, thus '9597195967' and '9596795959' and '959719596795959' are all three primes.

MATHEMATICA

ccatQ[n_]:=Module[{idn=IntegerDigits[n], pp=IntegerDigits[NextPrime[n, -1]], np= IntegerDigits[ NextPrime[n]]}, And@@PrimeQ[{FromDigits[ Join[np, idn]], FromDigits[Join[idn, pp]], FromDigits[Join[np, idn, pp]]}]]; Select[ Range[300000], ccatQ] (* Harvey P. Dale, Sep 09 2011 *)

CROSSREFS

Cf. A034808-A034821.

Sequence in context: A088894 A015277 A135418 * A210091 A068260 A252365

Adjacent sequences:  A034815 A034816 A034817 * A034819 A034820 A034821

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Oct 15 1998.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified December 22 07:03 EST 2014. Contains 252328 sequences.