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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A090264 Numbers n such that the strings n7n and 7n7 are both prime. 4
131, 153, 191, 233, 261, 327, 341, 359, 389, 407, 429, 459, 489, 527, 533, 579, 593, 599, 671, 683, 701, 723, 731, 797, 813, 869, 873, 939, 981, 1083, 1097, 1109, 1143, 1187, 1241, 1283, 1317, 1391, 1437, 1451, 1539, 1553, 1871, 1889, 1893, 2049, 2111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

EXAMPLE

131 is a member as 1317131 and 71317 are both prime.

CROSSREFS

Cf. A090262, A090263, A090265.

Sequence in context: A164294 A155924 A270237 * A132254 A087832 A335271

Adjacent sequences:  A090261 A090262 A090263 * A090265 A090266 A090267

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 28 2003

EXTENSIONS

More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 02 2004

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 December 1 12:50 EST 2020. Contains 338833 sequences. (Running on oeis4.)