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A208980 List of winning positions in Barry Cipra's Factor Subtractor game. 1
4, 9, 10, 14, 16, 18, 22, 25, 26, 28, 30, 34, 36, 40, 46, 48, 49, 54, 55, 56, 62, 63, 65, 66, 68, 74, 75, 76, 80, 81, 84, 88, 90, 94, 96, 100, 104, 105, 114, 115, 116, 119, 120, 121, 126, 132, 135, 138, 142, 144, 153, 154, 155, 156, 160, 162, 166, 168, 170, 174, 178, 182, 183, 184, 185, 190, 192, 196, 198, 202, 204 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A positive integer n is in the sequence if and only if it has a proper factorization, n=hk, for which neither n-h nor n-k is in the sequence.  (No prime is in the sequence, because no prime has a proper factorization.) [Barry Cipra, Mar 07 2012]

REFERENCES

Barry Cipra, Personal communication, Mar 02 2012

Barry Cipra, Factor Subtractor, 2012; reprinted in "Barrycades and Septoku: Papers in Honor of Martin Gardner and Tom Rogers", ed. Thane Plambeck and Tomas Rokicki, MAA Press, 2020, pp. 59-62.

LINKS

Matthew Richey, Table of n, a(n) for n = 1..85667

Barry Cipra, Factor Subtractor, 2012

CROSSREFS

Sequence in context: A028839 A141833 A140292 * A010426 A243170 A054294

Adjacent sequences:  A208977 A208978 A208979 * A208981 A208982 A208983

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mar 04 2012

STATUS

approved

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Last modified September 24 21:01 EDT 2020. Contains 337321 sequences. (Running on oeis4.)