login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A068682 Numbers n such that the concatenations n, n-2, n and n, n+2, n are primes. 0
3, 7, 17, 31, 49, 57, 111, 169, 269, 363, 389, 393, 637, 643, 671, 697, 787, 851, 853, 927, 1033, 1087, 1089, 1151, 1153, 1173, 1217, 1219, 1233, 1261, 1331, 1479, 1671, 1761, 1767, 1837, 1841, 1859, 1921, 2011, 2147, 2149, 2283, 2311, 2353, 2377, 2409 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..47.

EXAMPLE

17 belongs to this sequence for 171517 as well as 171917 are primes.

MATHEMATICA

d[n_] := IntegerDigits[n]; Select[Range[2410], And@@PrimeQ[FromDigits/@{Join[d[#], d[#-2], d[#]], Join[d[#], d[#+2], d[#]]}] &] (* Jayanta Basu, May 20 2013 *)

CROSSREFS

Cf. A068680, A068681.

Sequence in context: A228567 A123988 A006628 * A292446 A045425 A099983

Adjacent sequences:  A068679 A068680 A068681 * A068683 A068684 A068685

KEYWORD

base,hard,nonn

AUTHOR

Amarnath Murthy, Mar 02 2002

EXTENSIONS

More terms from Sascha Kurz, Mar 26 2002

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 22 19:39 EST 2020. Contains 331153 sequences. (Running on oeis4.)