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A084034 Numbers which are a product of repeated-digit numbers A010785. 11
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 27, 28, 30, 32, 33, 35, 36, 40, 42, 44, 45, 48, 49, 50, 54, 55, 56, 60, 63, 64, 66, 70, 72, 75, 77, 80, 81, 84, 88, 90, 96, 98, 99, 100, 105, 108, 110, 111, 112, 120, 121, 125, 126, 128 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Numbers which can be written as a*b*c*... where a, b, c are numbers whose decimal expansions are repetitions of a single digit.
Superset of A051038. The first numbers in this sequence but not in A051038 are 111, 222, 333, 444, 555. - R. J. Mathar, Sep 17 2008
From David A. Corneth, Aug 03 2017: (Start)
Closed under multiplication.
Multiples of 1-digit primes and numbers of the form (10^n - 1) / 9. (End)
LINKS
David A. Corneth, Table of n, a(n) for n = 1..12917 (Terms <= 10^8)
EXAMPLE
99 is a member since 99 = 3*33.
9768 is a member since 9768= 2*22*222.
111*2*33*44 = 322344 is a member.
MAPLE
isA010786 := proc(n) if nops(convert(convert(n, base, 10), set)) = 1 then true; else false ; fi; end: isA084034 := proc(n, a010785) local d ; if n = 1 then RETURN(true) ; fi; for d in ( numtheory[divisors](n) minus{1} ) do if d in a010785 then if isA084034(n/d, a010785) then RETURN(true) ; fi; fi; od: RETURN(false) ; end: nmax := 1000: a010785 := [] : for k from 1 to nmax do if isA010786(k) then a010785 := [op(a010785), k] ; fi; od: for n from 1 to nmax do if isA084034(n, a010785) then printf("%d, ", n) ; fi; end: # R. J. Mathar, Sep 17 2008
CROSSREFS
A002473 gives products of single-digit numbers.
Sequence in context: A033892 A033620 A033637 * A084347 A051038 A140332
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, May 26 2003
EXTENSIONS
Corrected and extended by David Wasserman, Dec 09 2004
Corrected data, offset changed to 1 by David A. Corneth, Aug 03 2017
Edited by N. J. A. Sloane, Jul 02 2017 and Oct 10 2018
STATUS
approved

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Last modified July 19 05:20 EDT 2024. Contains 374388 sequences. (Running on oeis4.)