A092992 -id:A092992 - cp's OEIS frontend

A092993 Smallest prime of the form concatenation(s) of prime(n) with itself followed by a 3, or 0 if no such prime exists.

23, 0, 53, 73, 113, 13131313133, 173, 193, 233, 293, 313, 373, 41413, 433, 47474747474747474747474747473, 53535353535353535353535353533, 593, 613, 673, 71713, 733, 0, 83833, 89898989893, 97973, 1013, 1033, 1071071071073, 1093

Offset: 1

Amarnath Murthy, Mar 28 2004

Start with p=prime(n). If concat(p,3) is prime, then this is a(n), else consider concat(p,p,3), and so on.

			For a(1), start with prime(1)=2. Since appending a digit 3 yields the prime 23, a(1)=23.
For a(2), start with prime(2)=3. Since concatenating any number of digits '3' never yields a prime, a(2)=0.
For a(6), starting with prime(6)=13, one has to take 5 concatenations of itself before a prime is obtained when a final digit '3' is appended, thus a(6)=13131313133.
a(22)=0 since the concatenation of prime(22)=79 with itself, followed by a 3, is always composite. - _Giovanni Resta_, Apr 07 2006

Cf. A092992, A092994, A092995.

a(15)-a(21) from Stefan Steinerberger, Nov 09 2005

More terms from Giovanni Resta, Apr 07 2006

A092994 Smallest prime of the form concatenation of prime(n) with itself followed by a 7, or 0 if no such prime exists.

Original entry on oeis.org

227, 37, 557, 0, 11117, 137, 17171717171717171717171717171717171717171717171717177, 197, 23232323232323237, 29297, 317, 0, 41414141414141414141414141414141414141414141417

Offset: 1

Amarnath Murthy, Mar 28 2004

a(12)=0 since the concatenation of 37 with itself, followed by a 7, is always composite. a(14), the term relative to 43, is a prime with 1089 digits. - Giovanni Resta, Apr 07 2006

Cf. A092992, A092993, A092995.

More terms from Giovanni Resta, Apr 07 2006

A092995 Smallest prime of the form concatenation of prime(n) with itself followed by a 9, or 0 if no such prime exists.

Original entry on oeis.org

29, 0, 59, 79, 11119, 139, 179, 199, 239, 29292929292929299, 31319, 379, 419, 439, 479, 0, 599, 619, 67679, 719, 739, 797979799, 839, 89899, 979797979, 1019, 1039, 1071071071079, 1091091091099, 1131139, 1279, 1319, 1371371371379, 1399, 1499

Offset: 1

Amarnath Murthy, Mar 28 2004

a(16)=0 since the concatenation of 53 with itself, followed by a 9, is always composite. a(36), if it exists, has more than 12000 digits. - Giovanni Resta, Apr 07 2006

Cf. A092992, A092993, A092994.

More terms from Sam Alexander, Jan 09 2005

More terms from Giovanni Resta, Apr 07 2006

cp's OEIS Frontend

A092993 Smallest prime of the form concatenation(s) of prime(n) with itself followed by a 3, or 0 if no such prime exists.

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A092994 Smallest prime of the form concatenation of prime(n) with itself followed by a 7, or 0 if no such prime exists.

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A092995 Smallest prime of the form concatenation of prime(n) with itself followed by a 9, or 0 if no such prime exists.

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