A077391 Smallest n-digit prime which leaves a prime at every step if most significant digit and least significant digit are deleted until a one digit or two digit prime is obtained, or 0 if no such prime exists.

2, 11, 127, 1021, 10313, 100237, 1002931, 10002331, 100023331, 1000023337, 10000239937, 100000233397, 1000002339937, 10000002339931, 100000139991331, 1000000023399331, 10000000233993397, 100000000293999997

Offset

1,1

Comments

Conjecture: No term is zero.

Links

Table of n, a(n) for n=1..18.

Example

a(6) = 100237: this is the smallest 6-digit number such that deleting MSD and LSD yields prime at every step, i.e. 100237, 0023, 02 all are primes.

Crossrefs

Cf. A077390.

Sequence in context: A206401 A193207 A112864 * A104087 A208858 A376126

Adjacent sequences: A077388 A077389 A077390 * A077392 A077393 A077394

Keyword

base,nonn

Author

Amarnath Murthy, Nov 07 2002

Extensions

More terms from Daniel Starodubtsev, May 05 2020

Status

approved