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 A351996 A chain reaction sequence: a digit d1 from a(n) is expelled towards a(n+1) where it hits a digit d2 [from a(n+1)] and replaces it; d2 in turn is expelled towards a(n+2), hits a digit d3 there and replaces it; d3 in turn is expelled towards a(n+3), hits a digit there, and replaces it; d4 is expelled... etc. At the end of the chain reaction, only prime numbers will be left. This is the lexicographically earliest sequence of distinct positive integers with this property. 4
 1, 10, 101, 103, 107, 109, 111, 11, 12, 2, 3, 4, 13, 14, 17, 15, 5, 6, 21, 7, 8, 19, 16, 27, 9, 18, 23, 29, 33, 20, 113, 30, 117, 31, 22, 39, 24, 37, 25, 43, 41, 47, 51, 49, 53, 59, 63, 57, 69, 61, 67, 71, 32, 73, 34, 77, 35, 79, 36, 81, 83, 89, 93, 26, 87, 99, 28, 121, 38, 123, 40, 119, 42, 127, 44, 91, 50 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS The sequence is a permutation of the positive integers. LINKS Eric Angelini, A chain reaction producing primes, personal blog of the author, Feb. 2022. EXAMPLE 1 is expelled from a(1) = 1 and hits the 0 of a(2) = 10, turning this integer into 11, a prime; 0 is expelled from a(2) = 10 and hits the 0 of a(3) = 101, leaving this prime unchanged; 0 is expelled from a(3) = 101 and hits the 0 of a(4) = 103, leaving this prime unchanged; 0 is expelled from a(4) = 103 and hits the 0 of a(5) = 107, leaving this prime unchanged; 0 is expelled from a(5) = 107 and hits the 0 of a(6) = 109, leaving this prime unchanged; 0 is expelled from a(6) = 109 and hits the middle 1 of a(7) = 111, turning this integer into 101, a prime; 1 is expelled from a(7) = 111 and hits one 1 of a(8) = 11, leaving this prime unchanged; 1 is expelled from a(8) = 11 and hits the 2 of a(9) = 12, turning this integer into 11, a prime; 2 is expelled from a(9) = 12 and hits the 2 of a(10) = 2, leaving this prime unchanged; etc. From Jon E. Schoenfield, Mar 01 2022: (Start) The chain reaction is depicted in the chart below: . | Step | Step | Step | Step | Step | Step | Step | Step | Step | Step | | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | | | | | | | | | | | | | : | | | | | | | | | | | 1 | | | | | | | | | | | 10 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | | | 0 | | | | | | | | | | 101 | 101 | 101 | 101 | 101 | 101 | 101 | 101 | 101 | 101 | | | | 0 | | | | | | | | | 103 | 103 | 103 | 103 | 103 | 103 | 103 | 103 | 103 | 103 | | | | | 0 | | | | | | | | 107 | 107 | 107 | 107 | 107 | 107 | 107 | 107 | 107 | 107 | | | | | | 0 | | | | | | | 109 | 109 | 109 | 109 | 109 | 109 | 109 | 109 | 109 | 109 | | | | | | | 0 | | | | | | 111 | 111 | 111 | 111 | 111 | 111 | 101 | 101 | 101 | 101 | | | | | | | | 1 | | | | | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | 11 | | | | | | | | | 1 | | | | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 12 | 11 | 11 | | | | | | | | | | 2 | | | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | (End) CROSSREFS Cf. A351997 (odd numbers left), A351998 (even numbers left), A351999 (Fibonacci numbers left), A352000 (square numbers left). Sequence in context: A231889 A066327 A277442 * A077712 A219763 A214390 Adjacent sequences: A351993 A351994 A351995 * A351997 A351998 A351999 KEYWORD base,nonn AUTHOR Eric Angelini and Carole Dubois, Feb 27 2022 STATUS approved

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Last modified November 29 13:18 EST 2022. Contains 358430 sequences. (Running on oeis4.)