A217560 Terms as well as digits have alternating primality; this is the lexicographically earliest injective sequence with this property.

1, 2, 4, 3, 6, 5, 8, 7, 9, 29, 20, 31, 21, 59, 24, 71, 26, 79, 28, 263, 12, 13, 15, 17, 42, 43, 45, 47, 62, 67, 63, 83, 65, 97, 82, 131, 30, 283, 85, 139, 34, 293, 87, 151, 36, 307, 92, 179, 38, 313, 93, 421, 39, 317, 95, 431, 50, 347, 120, 367, 121, 383, 124, 397, 126, 503, 128, 547, 129, 563, 130, 587, 134, 593, 136, 743, 138, 787

Offset: 1

Author

Eric Angelini and M. F. Hasler, Oct 06 2012

Keywords

• nonn
• base

Comments

Exactly every other term, and also every other digit (in concatenated terms) is prime.

Links

• Carole Dubois, Table of n, a(n) for n = 1..5292
• E. Angelini, Non-primes/primes: integers and digits alternate, SeqFan mailing list, Oct 06 2012
• Carole Dubois, Graph with even ranges and odd ranges separated

Crossrefs

The sequence A217559 is a simplified variant.

See also A217555, A217556, where "primality" is replaced by "parity".

Extensions

Values from a(26)=43 on corrected by Jean-Marc Falcoz, Oct 10 2012