A208980 - OEIS

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A208980

List of winning positions in Barry Cipra's Factor Subtractor game.

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 A356711

Adjacent sequences: A208977 A208978 A208979 * A208981 A208982 A208983

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mar 04 2012

STATUS

approved