A210417 -id:A210417 - cp's OEIS frontend

A210423 List the positions of all digits 9 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

2, 9, 4, 90, 7, 91, 92, 13, 93, 17, 94, 21, 95, 25, 96, 29, 97, 28, 35, 98, 39, 99, 38, 40, 47, 900, 52, 901, 57, 902, 62, 903, 67, 904, 72, 905, 77, 906, 82, 907, 87, 908, 999, 9999, 9990, 104, 909, 106, 113, 910, 119, 911, 118, 128, 912, 134, 913, 139, 143

Offset: 1

Paolo P. Lava, Mar 26 2012

See A210415 for comments, links, and code.

			The sequence cannot start with 1 because the first digit is not 9. Let us start with 2: the second digit is equal to 9. The third digit cannot be 3 because the third digit is not 9. So let it be 4. In the next position we now have 90 because it is the minimum number greater than 8 and starting with the digit 9. And so on.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000

Cf. A210414, A210415, A210416, A210417, A210418, A210419, A210420, A210421, A210422.

a(23)-a(26) corrected by Paolo P. Lava, Apr 17 2012

A210415 List the positions of all digits 1 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

Original entry on oeis.org

1, 3, 10, 6, 11, 7, 21, 13, 15, 17, 19, 101, 24, 100, 29, 102, 34, 103, 39, 104, 44, 105, 49, 106, 54, 107, 59, 108, 64, 109, 69, 110, 70, 76, 111, 77, 78, 85, 112, 86, 91, 94, 113, 95, 211, 1111, 11111, 1110, 115, 116, 118, 119, 121, 122, 124, 125, 127, 129

Offset: 1

Paolo P. Lava, Mar 26 2012

Original name: "A self-describing sequence: The a(n) say the positions of the digits 1 inside the sequence when it is read as a string of digits."
For each n, the digit in position a(n) is equal to 1. At each step, choose the minimum integer not yet present in the sequence and not leading to a contradiction.
This sequence had been mentioned by Wasserman in 2008, cf. A098645, a variant of this sequence with additional restriction a(n+1) > a(n). - M. F. Hasler, Oct 08 2013

			The sequence starts with 1: the first digit is equal to 1. In the second position we cannot write 2 because the second digit would not be 1 but 2. Then we write 3. The third digit must be 1 and the minimum number starting with 1 is 10. And so on.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000
Index to the OEIS: Entries related to self-referencing sequences.

This construction for other decimal digits is A210414, A210416, A210417, A210418, A210419, A210420, A210421, A210422, A210423.

Variants of this sequence include A098645, A098670, A114134, A167519.

#Returns the first n terms of this sequence for digit d
def dig_loc(d,n):
  L, S = [], ""
  while len(L)lenS or S[new-1]==str(d) ) and ( (new-lenS-1 not in range(ext)) or a[new-lenS-1]==str(d) ) and ( d!=0 or lenS+ext+1!=new ):
          L.append(new)
          S += str(new)
          break
        else: new = 0
  return L
dig_loc(1,58) # Danny Rorabaugh, Nov 27 2015

Edited by M. F. Hasler, Oct 10 2013

A210418 List the positions of all digits 4 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

Original entry on oeis.org

2, 4, 5, 44, 7, 40, 11, 41, 14, 17, 42, 21, 43, 24, 27, 45, 31, 46, 34, 37, 47, 54, 444, 4444, 48, 52, 404, 57, 400, 62, 401, 67, 402, 72, 403, 77, 405, 82, 406, 87, 407, 92, 408, 97, 409, 103, 410, 109, 411, 114, 118, 412, 124, 413, 123, 133, 414, 135, 140

Offset: 1

Paolo P. Lava, Mar 26 2012

See A210415 for comments, links, and code.

			The sequence cannot start with 1 because the first digit is not 4. Let us start with 2: the second digit is 4. So in the second position we have 4. The third digit cannot be 3 because the third digit is not 4. So let it be 5. In the next position we now have 44. And so on.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000

Cf. A210414, A210415, A210416, A210417, A210419, A210420, A210421, A210422, A210423.

Name edited and a(22)-a(59) corrected by Danny Rorabaugh, Nov 30 2015

A210419 List the positions of all digits 5 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

Original entry on oeis.org

2, 5, 4, 55, 7, 50, 11, 51, 15, 52, 14, 21, 53, 25, 54, 24, 31, 56, 35, 57, 34, 41, 58, 45, 59, 44, 65, 555, 5555, 550, 63, 505, 68, 500, 73, 501, 78, 502, 83, 503, 88, 504, 93, 506, 98, 507, 104, 508, 110, 509, 115, 119, 510, 125, 511, 124, 134, 512, 140, 513

Offset: 1

Paolo P. Lava, Mar 26 2012

See A210415 for comments, links, and code.

			The sequence cannot start with 1 because the first digit is not 5. Let us start with 2: the second digit is equal to 5. The third digit cannot be 3 because the third digit is not 5. So let it be 4. The next term must begin with a 5 because 4 is already in the sequence. Since 5 is also a previous term, it must be 55. With 2,4,5 already used, and 1,3,6 pointing at digits that are not 5, the next term must be 7.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000

Cf. A210414, A210415, A210416, A210417, A210418, A210420, A210421, A210422, A210423.

a(5)-a(90) corrected by Danny Rorabaugh, Nov 27 2015

A210420 List the positions of all digits 6 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

Original entry on oeis.org

2, 6, 4, 60, 61, 9, 62, 13, 63, 16, 19, 64, 23, 65, 26, 29, 66, 30, 35, 67, 39, 68, 43, 69, 46, 49, 600, 54, 601, 59, 666, 6666, 66660, 73, 602, 78, 603, 83, 604, 88, 605, 93, 606, 95, 101, 607, 106, 110, 608, 116, 609, 115, 125, 610, 131, 611, 136, 140, 612

Offset: 1

Paolo P. Lava, Mar 26 2012

See A210415 for comments, links, and code.

			The sequence cannot start with 1 because the first digit is not 6. Let us start with 2: the second digit is equal to 6. The third digit cannot be 3 because the third digit is not 6. So let it be 4. In the next position we now have 60 because it is the minimum number greater than 6 and starting with the digit 6. And so on.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000

Cf. A210414, A210415, A210416, A210417, A210418, A210419, A210421, A210422, A210423.

A210421 List the positions of all digits 7 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

Original entry on oeis.org

2, 7, 4, 70, 8, 77, 11, 71, 15, 72, 19, 73, 23, 74, 27, 75, 26, 33, 76, 37, 78, 36, 43, 79, 47, 700, 46, 54, 701, 59, 702, 64, 703, 69, 777, 7777, 77770, 83, 704, 87, 90, 705, 95, 706, 101, 707, 103, 110, 708, 116, 709, 122, 710, 127, 131, 711, 137, 712, 136

Offset: 1

Paolo P. Lava, Mar 26 2012

See A210415 for comments, links, and code.

			The sequence cannot start with 1 because the first digit is not 7. Let us start with 2: the second digit is equal to 7. The third digit cannot be 3 because the third digit is not 7. So let it be 4. In the next position we now have 70 because it is the minimum number greater than 7 and starting with the digit 7. And so on.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000

Cf. A210414, A210415, A210416, A210417, A210418, A210419, A210420, A210422, A210423.

Name edited and a(5)-a(31) corrected by Danny Rorabaugh, Nov 30 2015

A210422 List the positions of all digits 8 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

Original entry on oeis.org

2, 8, 4, 80, 7, 88, 11, 81, 15, 82, 18, 21, 83, 25, 84, 28, 31, 85, 35, 86, 38, 41, 87, 45, 89, 48, 51, 800, 56, 801, 61, 802, 66, 803, 71, 804, 76, 805, 98, 888, 8888, 880, 93, 806, 99, 881, 104, 807, 110, 808, 112, 118, 122, 809, 128, 810, 127, 137, 811

Offset: 1

Paolo P. Lava, Mar 26 2012

See A210415 for comments, links, and code.

			The sequence cannot start with 1 because the first digit is not 8. Let us start with 2: the second digit is equal to 8. The third digit cannot be 3 because the third digit is not 8. So let it be 4. In the next position we now have 80 because it is the minimum number greater than 8 and starting with the digit 8. And so on.

Danny Rorabaugh, Table of n, a(n) for n = 1..1000

Cf. A210414, A210415, A210416, A210417, A210418, A210419, A210420, A210421, A210423.

Name edited and a(25)-a(59) corrected by Danny Rorabaugh, Nov 30 2015

cp's OEIS Frontend

A210423 List the positions of all digits 9 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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A210415 List the positions of all digits 1 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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A210418 List the positions of all digits 4 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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A210419 List the positions of all digits 5 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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A210420 List the positions of all digits 6 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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A210421 List the positions of all digits 7 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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Extensions

A210422 List the positions of all digits 8 in the concatenation of all terms, not necessarily in order. This is the lexicographically earliest such sequence.

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