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A062845
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When expressed in base 2 and then interpreted in base 3, is a multiple of the original number.
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15
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0, 1, 5, 6, 10, 12, 30, 36, 60, 120, 180, 215, 216, 252, 360, 430, 432, 1080, 2730, 3276, 13710, 14724, 16380, 20520, 24624, 24840, 27125, 27420, 32760, 38880, 48606, 49091, 54250, 54840, 97212, 98280
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OFFSET
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1,3
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COMMENTS
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The numbers 2*m, 4*m and 8*m are also terms of the sequence for m=a(122). - Dimiter Skordev, Mar 29 2020
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LINKS
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Dimiter Skordev, Table of n, a(n) for n = 1..122 (terms < 10^15, terms 1..36 from Erich Friedman, 37..111 from Dimiter Skordev, 112..120 from Giovanni Resta)
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EXAMPLE
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30 = 11110_2; 11110_3 = 120 = 4*30.
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MATHEMATICA
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{0} ~Join~ Select[Range[10^5], Mod[ FromDigits[ IntegerDigits[#, 2], 3], #] == 0 &] (* Giovanni Resta, Dec 10 2019 *)
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PROG
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(Magma) [0] cat [k:k in [1..100000]|Seqint(Intseq(Seqint(Intseq(k, 2))), 3) mod k eq 0]; // Marius A. Burtea, Dec 29 2019
(PARI) isok(m) = (m==0) || fromdigits(digits(m, 2), 3) % m == 0; \\ Michel Marcus, Feb 15 2020
(Python)
def BaseUp(n, b):
up, b1 = 0, 1
while n > 0:
up, b1, n = up+(n%b)*b1, b1*(b+1), n//b
return up
n, k = 1, 0
print(1, 0)
while n < 35:
n, k = n+1, k+1
while BaseUp(k, 2)%k != 0:
k = k+1
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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