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A160234 Number of n-digit "early bird numbers" A116700. 0
0, 45, 630, 6896, 73059, 757755, 7773854 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

a(1) = 0 because there are no 1-digit terms in A116700;

a(1) = 45 because there are 45 2-digit terms in A116700:

12,21,23,31,32,34,41,42,43,45,51,52,53,54,56,61,62,63,64,65,67,71,72,73,74,75,76,78,81,82,83,84,85,86,87,89,91,92,93,94,95,96,97,98,99.

MATHEMATICA

s="1"; ss={}; Do[tsn=ToString[n]; If[ !StringFreeQ[s, tsn], AppendTo[ss, n]]; s=s<>tsn, {n, 2, 99999}]; Table[Length[Select[ss, 10^(n-1)<=#<10^n&]], {n, 1, 5}]

PROG

(Python)

from itertools import count, islice

def agen(): # generator of terms

s = ""

for digits in count(1):

c = 0

for k in range(10**(digits-1), 10**digits):

sk = str(k)

if sk in s: c += 1

s += sk

yield c

print(list(islice(agen(), 5))) # Michael S. Branicky, Mar 17 2022

CROSSREFS

Cf. A116700 ("Early bird" numbers).

Sequence in context: A189350 A090024 A282767 * A110691 A296540 A105251

Adjacent sequences: A160231 A160232 A160233 * A160235 A160236 A160237

KEYWORD

base,nonn,more

AUTHOR

Zak Seidov, May 04 2009

EXTENSIONS

a(6)-a(7) from Michael S. Branicky, Mar 17 2022

STATUS

approved

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Last modified November 27 10:03 EST 2022. Contains 358367 sequences. (Running on oeis4.)