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.

A043314 a(n)=A033008(n)/11.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 100, 102, 103, 104, 105, 106, 107, 108, 109, 200, 201, 203, 204, 205, 206, 207, 208, 209, 300, 301, 302, 304, 305, 306, 307, 308, 309, 400, 401, 402, 403, 405, 406, 407, 408, 409, 500, 501, 502, 503, 504
Offset: 1

Views

Author

Keywords

Comments

Also, numbers which, written in base 100, have all digits < 10 and no adjacent digits equal. - M. F. Hasler, Feb 03 2014

Crossrefs

Programs

  • PARI
    is_A043314(n)=(n=[n])&&!until(!n[1],((n=divrem(n[1],100))[2]<10 && n[1]%10!=n[2])||return) \\ M. F. Hasler, Feb 03 2014

A247241 In base 2, smallest positive integer k such that k contains all possible strings of n binary digits.

Original entry on oeis.org

2, 19, 558, 272060, 34949682936, 297564712194085870576, 10932581082490851526951746612437309648864, 7425338450010038712278392695279246718801455644988538421150211866664645481447360
Offset: 1

Views

Author

Anthony Sand, Nov 28 2014

Keywords

Comments

In base 2, there are 2^n distinct strings of n digits and the smallest positive integer to contain all of them will have 2^n+(n-1) digits (see A052944). For example, there are 2^2 = 4 distinct strings of two digits: 00, 01, 10, 11. All of them are represented in the 5-digit binary number 10011 = 19 in base 10.

Examples

			n = 1: a(1) = 2 = 10 in base 2, which contains 2 distinct strings of one digit: 1, 0.
n = 2: a(2) = 19 = 10011, which contains 4 distinct strings of two digits: 10, 00, 01, 11.
n = 3: a(3) = 558 = 1000101110, which contains 8 distinct strings of three digits: 100, 000, 001, 010, 101, 011, 111, 110.
n = 4: a(4) = 272060 = 1000010011010111100, which contains 16 distinct strings of four digits: 1000, 0000, 0001, 0010, 0100, 1001, 0011, 0110, 1101, 1010, 0101, 1011, 0111, 1111, 1110, 1100.
		

Crossrefs

A249907 Smallest positive integer k such that k contains all possible pairs of digits when represented in base b = n >= 2.

Original entry on oeis.org

19, 20842, 4387884733, 301083852338952371, 10372871309299412994565980691, 257810894191937039020949293796466032151538, 6291283822228991408060146690794416231996294644948906012153, 196933489270977741064964174271054692081510750312035993579769632880958095885917
Offset: 2

Views

Author

Anthony Sand, Nov 08 2014

Keywords

Comments

In base b, there are b^2 distinct pairs of digits and the smallest positive integer to contain all of them will have (b^2)+1 digits. For example, in base 2 there are 2^2 = 4 distinct pairs: 00, 01, 10, 11. All of them are represented in the 5-digit binary number 10011 = 19 in base 10.

Examples

			n = 2: a(2) = 19 = 10011 in base 2, which contains 4 distinct pairs of digits: 10, 00, 01, 11.
n = 3: a(3) = 20842 = 1001120221 in base 3, which contains 9 distinct pairs of digits: 10, 00, 01, 11, 12, 20, 22, 21.
n = 4: a(4) = 4387884733 = 10011202130322331 in base 4, which contains 16 distinct pairs of digits: 10, 00, 01, 11, 12, 20, 02, 21, 13, 30, 03, 32, 22, 23, 33, 31.
In base 10, all pairs from 00 to 99 are found in the 101 digits of [1, 0, 0, 1, 1, 2, 0, 2, 1, 3, 0, 3, 1, 4, 0, 4, 1, 5, 0, 5, 1, 6, 0, 6, 1, 7, 0, 7, 1, 8, 0, 8, 1, 9, 0, 9, 2, 2, 3, 2, 4, 2, 5, 2, 6, 2, 7, 2, 8, 2, 9, 3, 3, 4, 3, 5, 3, 6, 3, 7, 3, 8, 3, 9, 4, 4, 5, 4, 6, 4, 7, 4, 8, 4, 9, 5, 5, 6, 5, 7,5, 8, 5, 9, 6, 6, 7, 6, 8, 6, 9, 7, 7, 8, 7, 9, 8, 8, 9, 9, 1].
		

Crossrefs

Extensions

Edited: minor changes in the name, comment and example. - Wolfdieter Lang, Nov 21 2014
Showing 1-3 of 3 results.