The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A010354 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A010354

Base-8 Armstrong or narcissistic numbers (written in base 10).
(history; published version)

#30 by N. J. A. Sloane at Wed Apr 20 16:25:00 EDT 2022

STATUS

proposed

approved

#29 by Chai Wah Wu at Wed Apr 20 15:51:04 EDT 2022

STATUS

editing

proposed

#28 by Chai Wah Wu at Wed Apr 20 15:50:46 EDT 2022

PROG

(Python)

from itertools import islice, combinations_with_replacement

def A010354_gen(): # generator of terms

for k in range(1, 30):

a = tuple(i**k for i in range(8))

yield from (x[0] for x in sorted(filter(lambda x:x[0] > 0 and tuple(int(d, 8) for d in sorted(oct(x[0])[2:])) == x[1], \

((sum(map(lambda y:a[y], b)), b) for b in combinations_with_replacement(range(8), k)))))

A010354_list = list(islice(A010354_gen(), 20)) # Chai Wah Wu, Apr 20 2022

STATUS

approved

editing

#27 by Andrew Howroyd at Fri Jan 17 14:10:40 EST 2020

STATUS

proposed

approved

#26 by Michel Marcus at Fri Jan 17 01:12:19 EST 2020

STATUS

editing

proposed

#25 by Michel Marcus at Fri Jan 17 01:12:14 EST 2020

LINKS

D. T. Winter, <a href="http://ftp.cwi.nl/dik/Armstrong">Table of Armstrong Numbers</a>

STATUS

proposed

editing

#24 by Jon E. Schoenfield at Fri Jan 17 00:27:41 EST 2020

STATUS

editing

proposed

#23 by Jon E. Schoenfield at Fri Jan 17 00:27:35 EST 2020

NAME

Base -8 Armstrong or narcissistic numbers (written in base 10).

LINKS

Joseph Myers, <a href="/A010354/b010354.txt">Table of n, a(n) for n = 1..62</a> (the full list of terms, from Winter)

EXAMPLE

20 = 24[_8] (in base 8), and 2^2 + 4^2 = 20.

432 = 660[_8], , and 6^3 + 6^3 + 0^3 = 432; it's easy to see that 432 + 1 then also satisfies the equation, as for any term that is a multiple of 8. (End)

AUTHOR

N. J. A. Sloane.

STATUS

approved

editing

#22 by Susanna Cuyler at Thu Nov 21 00:07:05 EST 2019

STATUS

proposed

approved

#21 by M. F. Hasler at Wed Nov 20 23:09:57 EST 2019

STATUS

editing

proposed