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.

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

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 * A397316 A249782 A090564

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