A075607 -id:A075607 - cp's OEIS frontend

A075609 a(1) = 1, a(n) = smallest prime number not occurring earlier such that the concatenation a(n-1) and a(n) is a prime.

1, 3, 7, 19, 13, 61, 31, 37, 67, 79, 103, 43, 73, 127, 139, 97, 151, 157, 109, 199, 181, 193, 163, 211, 229, 223, 241, 271, 277, 331, 283, 397, 337, 313, 307, 367, 457, 421, 349, 373, 379, 433, 439, 409, 463, 523, 487, 601, 541, 547, 499, 571, 673, 613, 577

Offset: 1

Amarnath Murthy, Sep 28 2002

Cf. A075607, A075608, A075610.

More terms from Michel ten Voorde Jun 23 2003

A075608 a(1) = 1, a(n) = smallest composite number not occurring earlier such that the concatenation a(n-1) and a(n) is a prime.

Original entry on oeis.org

1, 9, 77, 27, 49, 33, 91, 51, 133, 39, 119, 69, 143, 21, 121, 57, 203, 93, 169, 63, 247, 81, 299, 147, 209, 123, 217, 87, 187, 111, 253, 153, 259, 99, 289, 129, 221, 159, 161, 141, 301, 177, 319, 117, 329, 201, 287, 219, 361, 183, 343, 237, 581, 171, 341, 273, 323

Offset: 1

Amarnath Murthy, Sep 28 2002

Cf. A075607, A075609, A075610.

More terms from Michel ten Voorde Jun 23 2003

A075610 a(1) = 1, a(n) = smallest prime number not occurring earlier such that the concatenation a(n-1) and a(n) is a composite number.

Original entry on oeis.org

1, 2, 5, 7, 11, 13, 3, 19, 17, 29, 23, 31, 41, 37, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 97, 89, 103, 101, 109, 107, 113, 127, 131, 137, 139, 149, 151, 167, 157, 173, 163, 179, 181, 191, 193, 197, 199, 223, 227, 211, 233, 229, 239, 241, 251, 269, 263, 271, 257, 277

Offset: 1

Amarnath Murthy, Sep 28 2002

Cf. A075607, A075608, A075609.

More terms from Michel ten Voorde Jun 23 2003

A289994 a(1) = 1, a(2) = 2, a(n) = smallest number not occurring earlier such that the concatenation a(n-2), a(n-1) and a(n) is a prime.

Original entry on oeis.org

1, 2, 7, 11, 19, 13, 9, 21, 43, 3, 31, 49, 17, 37, 29, 41, 27, 39, 67, 33, 81, 53, 51, 23, 89, 91, 59, 47, 73, 61, 87, 99, 79, 63, 117, 113, 77, 127, 103, 93, 111, 71, 69, 101, 147, 57, 97, 133, 119, 121, 139, 131, 107, 157, 151, 123, 153, 83, 143, 169, 109, 137

Offset: 1

Seiichi Manyama, Sep 02 2017

			127, 2711, 71119, 111913, ... are primes.

Seiichi Manyama, Table of n, a(n) for n = 1..1000

Cf. A075607, A073676, A083754, A110772.

cp's OEIS Frontend

A075609 a(1) = 1, a(n) = smallest prime number not occurring earlier such that the concatenation a(n-1) and a(n) is a prime.

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A075608 a(1) = 1, a(n) = smallest composite number not occurring earlier such that the concatenation a(n-1) and a(n) is a prime.

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Extensions

A075610 a(1) = 1, a(n) = smallest prime number not occurring earlier such that the concatenation a(n-1) and a(n) is a composite number.

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Extensions

A289994 a(1) = 1, a(2) = 2, a(n) = smallest number not occurring earlier such that the concatenation a(n-2), a(n-1) and a(n) is a prime.

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