A275432 P-positions for the subtraction game whose allowed moves are the practical numbers (A005153).

0, 3, 10, 13, 44, 47, 102, 105, 146, 149, 232, 235, 636, 639, 814, 817, 950, 953, 1208, 1211, 2994, 2997, 4922, 4925, 4996, 4999, 6748, 6751, 8026, 8029, 8478, 8481, 12092, 12095, 14004, 14007, 31934, 31937, 35824, 35827, 41568, 41571, 46118, 46121, 60056, 60059, 62530, 62533, 106986, 106989

Offset: 0

Author

David Eppstein, Nov 20 2016

Keywords

• nonn

Comments

According to a general theorem of Golomb (1966) on subtraction games, this sequence is infinite, and more strongly (because of known results on the density of A005153) the number of terms below any given n is at least logarithmic in n.

Examples

			For instance, 10 is a P-position because each of the available moves (subtracting 1, 2, 4, 6, or 8 to yield 9, 8, 6, 4, or 2) can be countered: from 8, 6, 4, or 2, it is possible to win by moving directly to 0 and from 9 it is possible to win by subtracting 6 and moving to the smaller P-position 3.
		

Links

• S. W. Golomb, A mathematical investigation of games of "take-away", J. Combinatorial Theory, 1 (1966), 443-458.

Crossrefs

Cf. A030193.