The On-Line Encyclopedia of Integer Sequences (OEIS)

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Revision History for A215009

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A215009

Numbers which are "easy" to key on a computer numpad.
(history; published version)

#23 by Andrey Zabolotskiy at Thu Sep 01 03:45:33 EDT 2022

STATUS

editing

approved

#22 by Andrey Zabolotskiy at Thu Sep 01 03:45:15 EDT 2022

MATHEMATICA

(Python)

from itertools import count, islice

m = {'0':'12', '1':'024', '2':'0135', '3':'26', '4':'157', '5':'2468', '6':'359', '7':'48', '8':'579', '9':'68'}

def c(r): return (r=='0' or r[0]!='0') and not ("102" in r or "201" in r)

def agen():

reach = list("0123456789")

for d in count(1):

yield from (int(r) for r in reach if c(r))

reach = [r + s for r in reach for s in m[r[-1]]]

print(list(islice(agen(), 62))) # Michael S. Branicky, Jul 05 2022

PROG

(Python)

from itertools import count, islice

m = {'0':'12', '1':'024', '2':'0135', '3':'26', '4':'157', '5':'2468', '6':'359', '7':'48', '8':'579', '9':'68'}

def c(r): return (r=='0' or r[0]!='0') and not ("102" in r or "201" in r)

def agen():

reach = list("0123456789")

for d in count(1):

yield from (int(r) for r in reach if c(r))

reach = [r + s for r in reach for s in m[r[-1]]]

print(list(islice(agen(), 62))) # Michael S. Branicky, Jul 05 2022

STATUS

approved

editing

#21 by N. J. A. Sloane at Tue Jul 05 23:14:55 EDT 2022

STATUS

proposed

approved

#20 by Michael S. Branicky at Tue Jul 05 16:57:18 EDT 2022

STATUS

editing

proposed

#19 by Michael S. Branicky at Tue Jul 05 16:57:16 EDT 2022

MATHEMATICA

(Python)

from itertools import count, islice

m = {'0':'12', '1':'024', '2':'0135', '3':'26', '4':'157', '5':'2468', '6':'359', '7':'48', '8':'579', '9':'68'}

def c(r): return (r=='0' or r[0]!='0') and not ("102" in r or "201" in r)

def agen():

reach = list("0123456789")

for d in count(1):

yield from (int(r) for r in reach if c(r))

reach = [r + s for r in reach for s in m[r[-1]]]

print(list(islice(agen(), 62))) # Michael S. Branicky, Jul 05 2022

STATUS

approved

editing

#18 by Charles R Greathouse IV at Sun Feb 12 17:24:18 EST 2017

STATUS

editing

approved

#17 by Charles R Greathouse IV at Sun Feb 12 17:24:13 EST 2017

COMMENTS

A 10-automatic sequence. - Charles R Greathouse IV, Aug 01 2012

LINKS

<a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.

STATUS

approved

editing

#16 by N. J. A. Sloane at Thu Aug 02 17:20:06 EDT 2012

STATUS

reviewed

approved

#15 by Charles R Greathouse IV at Wed Aug 01 23:10:27 EDT 2012

STATUS

proposed

reviewed

Discussion

Thu Aug 02

04:52

Joerg Arndt: General setting:  n-digit numbers are length-n walks through a graph with vertices 0,1,...,9 and edges as defined in Mathematica code. Correct?
(I wonder about the "102" and "201";
 and also about "03", "04", etc because "0" is adjacent to "1" and "2" only).

#14 by Charles R Greathouse IV at Wed Aug 01 17:55:06 EDT 2012

STATUS

editing

proposed

Discussion

Wed Aug 01

21:46

Alonso del Arte: What would you say is the suitability of these numbers for ATM PINs? e.g., 5458 or 5256?

23:08

Charles R Greathouse IV: On ATMs the 0 is usually adjacent to the 8 instead of the 1 and 2.

23:10

Charles R Greathouse IV: Let me say it now: out of all base,dumb sequences this one is my favorite.