cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A167524 Erroneous version of A114308.

Original entry on oeis.org

1, 4, 6, 7, 8, 9, 11, 12, 13, 15, 17, 19, 30, 40, 42, 46, 48, 49, 60, 62, 64, 66, 67
Offset: 1

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Author

Keywords

A125132 Self-describing sequence: sequence starts with a(1) = 1 and a(n) is chosen to be the smallest positive number not already in the sequence such that the assertion "sequence gives the positions of the odd digits when the sequence is read as a string of digits" is true.

Original entry on oeis.org

1, 3, 5, 2, 7, 8, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 110, 10, 12, 14, 16, 111, 28, 30, 32, 34, 36, 48, 50, 52
Offset: 1

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Author

N. J. A. Sloane, Jan 12 2007

Keywords

Comments

Inspired by Angelini's sequence A114308.

Examples

			Here are the digits strung together (the odd digits occur at positions that are indexed by terms of the sequence):
-135278911
1315171921
2325272931
3335373941...
Explanation: a(2)=2? No. a(2)=3? Yes, but then the third term has to be odd and 2 has to appear later. a(3)=2? No, a(3) must be odd, so 5. a(4)? Now we can fill in the 2 that has been waiting. And so on.
		

Crossrefs

Cf. A125133 (missing numbers), A114308 (same except need a(n) > a(n-1)).

Extensions

Corrected and extended by D. S. McNeil, Oct 22 2011

A342164 A self-describing sequence: start with 0, then for each digit in each successive term, starting from the first term, append to the sequence its most recent position in the string formed by the concatenation of all previous terms.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 17, 19, 16, 23, 18, 27, 30, 27, 22, 27, 24, 39, 41, 44, 28, 47, 50, 41, 52, 56, 50, 56, 56, 56, 50, 56, 53, 72, 42, 75, 54, 80, 80, 76, 83, 80, 85, 92, 90, 80, 54, 99, 94, 99, 86, 99, 98, 99, 108, 99, 108, 99, 108, 99, 126, 99
Offset: 0

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Author

Scott R. Shannon, Mar 03 2021

Keywords

Comments

After the leading zero taking the a(n)-th digit of the sequence returns the digits of the sequence.

Examples

			The second term is 1 as the 0 in the first term appears as the first digit in the sequence. Likewise the third term is 2 as the 1 in the second term is the second digit of the sequence, and so on to the eleventh term.
As the eleventh term is 10 and has two digits, the twelfth and thirteenth terms give the most recent position of a 1 and 0 in the sequence, and they appear at the eleventh and twelfth position.
As the twelfth term is 11, the fourteenth and fifteenth terms give the most recent position of the two 1's. The last 1 appears at the fifteenth position, and after appending 15, which contains a 1, the most recent 1 now appears at the seventeenth position.
		

Crossrefs

Showing 1-3 of 3 results.