

A106007


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


1



0, 1, 13, 14, 15, 18, 19, 24, 25, 26, 28, 29, 35, 36, 37, 39, 45, 46, 48, 49, 52, 55, 59, 64, 65, 66, 69, 73, 75, 78, 79, 81, 82, 85, 89, 91, 95, 99, 125, 126, 127, 128, 129, 134, 135, 136, 137, 138, 143, 144, 145, 146, 147, 148, 149, 152, 153, 154, 155, 156, 157, 158
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OFFSET

0,3


COMMENTS

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 It is known that there are infinitely many Coster numbers (result of David Kloet, Albert Hendriks and Arjen Stolk, unpublished).


LINKS

Matthijs Coster, Feb 02 2007, Table of n, a(n) for n = 0..89
Matthijs Coster, www.wiskundemeisjes.nl/20061030/costergetallen/ (in Dutch)
Matthijs Coster, www.matcos.nl/sequences
Pythagoras, www.pythagoras.nu (in Dutch)


EXAMPLE

36 is in the sequence since 3*6+3*6 = 36


CROSSREFS

Cf. A036057.
Sequence in context: A293831 A118140 A108854 * A048037 A171492 A054031
Adjacent sequences: A106004 A106005 A106006 * A106008 A106009 A106010


KEYWORD

base,nonn


AUTHOR

Matthijs Coster, Dec 31 2006, Feb 02 2007


STATUS

approved



