A068651 Primes in which a string of 2's is sandwiched between two 9's.

929, 9222229, 9222222222229

Offset: 1

Author

Amarnath Murthy, Feb 28 2002

Keywords

• base
• nonn
• hard

Comments

The next term consists of 109 2's sandwiched between two 9's. - Sascha Kurz, Mar 27 2002

Links

• Amiram Eldar, Table of n, a(n) for n = 1..4
• Patrick De Geest, PDP Reference Table - 929.
• Makoto Kamada, Prime numbers of the form 922...229.
• Index entries for primes involving repunits.

Crossrefs

Cf. A068645, A068646, A068647, A068648, A068649, A068650, A056265, A082718.

Formula

a(n) = (830*10^A056265(n) + 61)/9 = (83*10^(A082718(n)-1) + 61)/9. [corrected by Amiram Eldar, Jul 27 2025]

Extensions

Edited by Ray Chandler, Oct 20 2010

Edited by Ray Chandler, Nov 05 2014