A229123 a(n) gives the number of bases, b>1, in which n is an early bird.

0, 0, 1, 0, 2, 2, 3, 2, 3, 2, 4, 3, 6, 4, 5, 3, 7, 2, 7, 5, 7, 6, 7, 4, 9, 7, 6, 5, 8, 5, 10, 4, 8, 8, 7, 5, 13, 8, 8, 6, 12, 7, 12, 7, 8, 11, 11, 5, 13, 9, 12, 9, 11, 5, 13, 11, 13, 12, 12, 5, 17, 11, 11, 8, 13, 9, 14, 9, 12, 7, 14, 8, 18, 11, 9, 11, 13, 11

Offset: 1

Author

Paul Tek, Sep 14 2013

Keywords

• nonn
• base

Comments

A number n is called an early bird in base b, if its digits in base b appear in the concatenation of the digits in base b of the numbers from 1 to n-1.

Examples

			The number 1 is never an early bird, so a(1)=0.
The number 3 is an early bird only in base 2, so a(3)=1.
The number 7 is an early bird in bases 2, 3 and 5, so a(7)=3.
		

Links

• Paul Tek, Table of n, a(n) for n = 1..10000
• Paul Tek, C program for this sequence
• Paul Tek, Illustration of the bases in which n is an early bird, where n ranges from 1 to 1000

Crossrefs

Cf. A116700, A161373, A135549.

Programs

C

See Link section.