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A332810
Number of integers in range 1..n that are not encountered on any of the possible paths from n to 1 when iterating with nondeterministic map k -> k - k/p, where p is any prime factor of k.
4
0, 0, 0, 1, 1, 1, 1, 4, 3, 4, 4, 5, 5, 5, 5, 11, 11, 9, 9, 12, 9, 12, 12, 15, 16, 15, 17, 16, 16, 16, 16, 26, 16, 26, 17, 24, 24, 24, 24, 30, 30, 25, 25, 31, 27, 31, 31, 37, 31, 38, 37, 38, 38, 40, 39, 41, 40, 41, 41, 42, 42, 42, 43, 57, 43, 43, 43, 58, 43, 46, 46, 57, 57, 57, 54, 58, 47, 58, 58, 68, 66, 68, 68, 62, 69, 62, 62, 72, 72
OFFSET
1,8
LINKS
FORMULA
a(n) = n - A332809(n).
EXAMPLE
a(12): we have three alternative paths: {12, 8, 4, 2, 1}, {12, 6, 4, 2, 1} or {12, 6, 3, 2, 1}, with [5, 7, 9, 10, 11] being the only numbers in range 1..12 that do not occur in any of those paths, therefore a(12) = 5.
PROG
(PARI)
up_to = 105;
A332809list(up_to) = { my(v=vector(up_to)); v[1] = Set([1]); for(n=2, up_to, my(f=factor(n)[, 1]~, s=Set([n])); for(i=1, #f, s = setunion(s, v[n-(n/f[i])])); v[n] = s); apply(length, v); }
v332809 = A332809list(up_to);
A332810(n) = (n-v332809[n]);
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 04 2020
STATUS
approved