A069791 Primes which yield primes each time the process of removing two outermost digits is carried out until finally a two digit prime (possibly with a leading 0) is obtained.

1021, 1031, 1033, 1039, 1051, 1117, 1171, 1193, 1231, 1237, 1291, 1297, 1319, 1373, 1433, 1439, 1471, 1531, 1597, 1613, 1619, 1733, 1831, 1973, 1979, 2027, 2029, 2039, 2053, 2111, 2113, 2131, 2137, 2179, 2237, 2239, 2293, 2297, 2311, 2371

Offset

1,1

Links

Table of n, a(n) for n=1..40.

Example

101737 is a member as the number obtained by removing the first and the last digit 0173 is a prime and further removing the first and the last digit gives another prime 17.

Mathematica

Select[Prime[Range[PrimePi[1000]+1, PrimePi[9999]]], PrimeQ[FromDigits[Rest[Most[IntegerDigits[#]]]]]&] (* Harvey P. Dale, Jan 04 2011 *)

Crossrefs

Cf. A069686.

Sequence in context: A102925 A216115 A024020 * A167846 A303918 A371378

Adjacent sequences: A069788 A069789 A069790 * A069792 A069793 A069794

Keyword

base,nonn

Author

Amarnath Murthy, Apr 09 2002

Extensions

Corrected by T. D. Noe, Nov 01 2006

Corrected and extended by Harvey P. Dale, Jan 04 2011

Status

approved