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 A217560 Terms as well as digits have alternating primality; this is the lexicographically earliest injective sequence with this property. 4
 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 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". 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 Jean-Marc Falcoz, Oct 10 2012 STATUS approved

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Last modified September 25 09:40 EDT 2021. Contains 347654 sequences. (Running on oeis4.)