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A217560 Terms as well as digits have alternating primality; this is the lexicographically earliest injective sequence with this property. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

LINKS

Table of n, a(n) for n=1..78.

E. Angelini, Non-primes/primes: integers and digits alternate, SeqFan mailing list, Oct 06 2012

CROSSREFS

The sequence A217559 is a simplified variant.

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

Sequence in context: A073846 A110458 A217559 * A114112 A113981 A234519

Adjacent sequences:  A217557 A217558 A217559 * A217561 A217562 A217563

KEYWORD

nonn,base

AUTHOR

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

EXTENSIONS

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

STATUS

approved

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Last modified August 16 16:12 EDT 2018. Contains 313809 sequences. (Running on oeis4.)