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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A090276 Least number with identical digits such that the concatenation a(n) a(n-1) ...a(2)a(1) a(2) ... a(n-1) a(n) is a prime. 1
2, 7, 3, 33, 9, 77, 33, 999, 1111111, 3, 33, 777777, 111111111, 77, 333333, 111, 99999999, 3333333333, 777777, 1, 33333333333333333333, 999999999999999999999999999999999999, 99999999, 999999999999999999999999999999999999999999, 3333333333333333333333333 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The resulting primes are given in A090275.

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

2,727,37273,... etc. are primes.

CROSSREFS

Cf. A090275.

Sequence in context: A229610 A117809 A052091 * A249782 A090564 A306618

Adjacent sequences:  A090273 A090274 A090275 * A090277 A090278 A090279

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 28 2003

EXTENSIONS

More terms from Sam Alexander, Jan 06 2005

Many further terms from David Wasserman, Oct 27 2005

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 March 7 19:13 EST 2021. Contains 341928 sequences. (Running on oeis4.)