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URL: https://oeis.org/A074100

⇱ A074100 - OEIS

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A074100
Cubes using only digits 1, 2, 3, 5 and 7.
3
1, 27, 125, 512, 1331, 3375, 753571, 2571353, 5177717, 17173512, 25153757, 72511713, 11512557512, 22211737731, 27135225125, 125375375125, 552377215125, 2252212155712, 3531251132352, 7127771131125, 23771111713777, 31122112521375, 37521355131352, 125112533753375
OFFSET
1,2
COMMENTS
Conjecture: the sequence is finite.
Opposite conjecture: the sequence is infinite. The frequency of terms with k digits is 4, 3, 5, 5, 9, 11, 12, 13, 22, 29, 33, 37, 49, 49, 78 for k = 1..15 respectively. - David A. Corneth, Mar 17 2019
LINKS
David A. Corneth, Table of n, a(n) for n = 1..359 (Terms < 10^45; first 37 terms from Jayanta Basu)
EXAMPLE
137^3 = 2571353, smallest term using the five digits 1, 2, 3, 5 and 7. - Bernard Schott, Mar 18 2019
91^3 = 753571 as 753571 uses only digits from 1, 2, 3, 5 and 7. It's fine that 91 doesn't. - David A. Corneth, Mar 18 2019
MATHEMATICA
t1 = Prepend[Prime[Range[4]], 1]; Select[Range[35000]^3, Complement[IntegerDigits[#], t1] == {} &] (* Jayanta Basu, Jul 31 2013 *)
PROG
(Python)
A074100_list = [n**3 for n in range(1, 10**6) if set(str(n**3)) <= set('12357')] # Chai Wah Wu, Mar 16 2019
CROSSREFS
Cf. A079656.
Sequence in context: A371189 A126272 A016755 * A082610 A061434 A092770
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Aug 21 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 30 2003
Two more terms from Jayanta Basu, Jul 31 2013
STATUS
approved