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Coster numbers: similar to Friedman numbers (A036057), but here the operations + - * / are allowed. All digits of a number have to be used exactly twice.

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`%I #9 Dec 12 2016 02:33:06
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`%S 0,1,13,14,15,18,19,24,25,26,28,29,35,36,37,39,45,46,48,49,52,55,59,
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`%T 64,65,66,69,73,75,78,79,81,82,85,89,91,95,99,125,126,127,128,129,134,
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`%U 135,136,137,138,143,144,145,146,147,148,149,152,153,154,155,156,157,158
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`%N Coster numbers: similar to Friedman numbers (A036057), but here the operations + - * / are allowed. All digits of a number have to be used exactly twice.
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`%C These numbers were introduced in 2006 in the yearly number puzzle in the Dutch Journal "Pythagoras" (see http://www.pythagoras.nu). It is known that there are infinitely many Coster numbers (result of David Kloet, Albert Hendriks and Arjen Stolk, unpublished).
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`%H Matthijs Coster, Feb 02 2007, <a href="/A106007/b106007.txt">Table of n, a(n) for n = 0..89</a>
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`%H Matthijs Coster, <a href="http://www.wiskundemeisjes.nl/20061030/coster-getallen/">www.wiskundemeisjes.nl/20061030/coster-getallen/</a> (in Dutch)
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`%H Matthijs Coster, <a href="http://www.matcos.nl/sequences/index.html#A106007">www.matcos.nl/sequences</a>
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`%H Pythagoras, <a href="http://www.pythagoras.nu">www.pythagoras.nu</a> (in Dutch)
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`%e 36 is in the sequence since 3*6+3*6 = 36
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`%Y Cf. A036057.
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`%K base,nonn
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`%O 0,3
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`%A _Matthijs Coster_, Dec 31 2006, Feb 02 2007
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