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.

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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

Views

Author

Paolo P. Lava, Mar 26 2012

Keywords

Comments

See A210415 for comments, links, and code.

Examples

			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.

Links

Crossrefs

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

Extensions

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

A098670 Start with a(1) = 5. Construct slowest growing sequence such that the statement "the a(n)-th digit is a 2" is true for all n.

Original entry on oeis.org

5, 6, 7, 8, 22, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 265, 266, 267, 268, 269, 270
Offset: 1

Views

Author

Eric Angelini, Oct 27 2004

Keywords

Comments

The sequence goes 5, 6, 7, 8, 22, 220, 221, ..., 290, 2222, 22222, 222222, ... for 275 more digits, then for most of the rest of the sequence, a(n+1)=a(n)+1. Starting with a(1)=3 yields 3, 4, 22, 23, ..., 30, 32, 222, 2222, 2223,... for at least 2000 more digits. (The 222nd digit happens to be the initial digit of a(63)=2271.) Starting with a(1)=4 yields 4, 5, 6, 22, 23, ..., 30, 222, 2222, 2223, ... See A210416 for a variant without requirement of growth. - M. F. Hasler, Oct 08 2013

Examples

			The 5th digit of the sequence is a "2", the 6th digit also, then the 7th, the 8th, the 22nd etc.

Links

Crossrefs

Cf. A114134, A098645, A210414-A210423.

Programs

  • PARI
    { a=5; P=Set(); L=0; while(1, print1(a,", "); P=setunion(P,Set([a])); L+=#Str(a); until(g, g=1; a++; s=Vec(Str(a)); for(i=1,#s, if(setsearch(P,L+i)&&s[i]!="2",g=0;break)); ); ) } \\ Max Alekseyev

Extensions

Edited and extended by Max Alekseyev, Feb 06 2010

A114134 Start with a(1) = 1. For n>1, choose a(n) to be the smallest number > a(n-1) consistent with the condition that "the a(n)-th digit is a 1" is true for all n.

Original entry on oeis.org

1, 3, 10, 11, 12, 21, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 1111, 11111, 111111, 1111111, 11111111, 11111112, 11111113
Offset: 1

Views

Author

Eric Angelini, Oct 27 2004

Keywords

Comments

There can be 1's in other positions too.
Sequence A098645 does not allow 1's in other positions, A210415 is a variant which does not impose a(n)>a(n-1). - M. F. Hasler, Oct 08 2013

Examples

			The first digit of the sequence is a "1", the 3rd digit also, then the 10th, the 11th, etc.

Links

Crossrefs

Cf. A098670. See A098645 for another version.
Cf. A210414-A210423.

Extensions

Entry revised by Eric Angelini and N. J. A. Sloane, Feb 03 2006.
More terms from Rick L. Shepherd, Feb 05 2006
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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