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.

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

1,1

Comments

See A210415 for comments, links, and code.

Links

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

Example

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.

Crossrefs

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

Sequence in context: A229789 A357240 A307131 * A206484 A061083 A177039

Adjacent sequences: A210416 A210417 A210418 * A210420 A210421 A210422

Keyword

nonn,base

Author

Paolo P. Lava, Mar 26 2012

Extensions

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

Status

approved