

A061310


Numbers which cannot be reached in the Countdown Numbers Game starting from (1,2,3,4,5,6): the game allows brackets and the operations +  x and / and not all numbers need be used, while the result of each partial calculation must be an integer.


1



284, 307, 309, 314, 317, 379, 394, 398, 403, 411, 417, 423, 429, 431, 433, 435, 436, 437, 439, 441, 442, 443, 445, 446, 447, 449, 451, 453, 454, 457, 458, 459, 461, 463, 464, 466, 467, 469, 471, 473, 474, 487, 489, 491, 493, 494, 496, 499, 502, 506, 509
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Starting with (1,1,1,1,1,1) no number greater than 9 can be reached.
Every number greater than 1080 = 6*5*4*3*(2+1) is in the sequence.  Sean A. Irvine, Feb 07 2023


LINKS



EXAMPLE

283 is not in the sequence since 283=((6+1)*5*4*2)+3; 285 is not in the sequence since 285=((6*5*2)3)*(4+1). However there is no similar calculation for 284 so 284 is in the sequence.


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



