



1, 1, 2, 1, 4, 1, 4, 4, 3, 2, 8, 3, 7, 7, 9, 2, 8, 5, 10, 10, 8, 6, 19, 6, 12, 9, 9, 8, 22, 9, 12, 12, 15, 10, 31, 9, 11, 14, 24, 13, 23, 9, 24, 17, 16, 10, 35, 15, 23, 25, 20, 12, 40, 17, 34, 21, 18, 14, 37, 17, 24, 25, 41, 20, 39, 14, 31, 34, 33, 18, 42, 16, 32, 37, 41, 18, 44, 25
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OFFSET

2,3


COMMENTS

antiphi(n) = the number of integers < n that are not divisible by any antidivisor of n.
The old definition given for this sequence was: antiphi(n) = number of integers <= n that are coprime to the antidivisors of n. However this does not match the entries.
See A066272 for definition of antidivisor.


LINKS



EXAMPLE

10 has antidivisors 3,4,7. The numbers not divisible by any of 3,4,7 and less than 10 are 1,2,5. Therefore antiphi(10)=3.


MAPLE

# needs antidivisors() as implemented in A066272
A066452 := proc(n)local ad, isad, j, k, totad:ad:=antidivisors(n):totad:=0:for j from 1 to n1 do isad:=1:for k from 1 to nops(ad) do if(j mod ad[k]=0)then isad:=0:break: fi:od:totad:=totad+isad:od:return totad:end:


PROG

(Python)
....return len([x for x in range(1, n) if all([x % d for d in range(2, n) if (n % d) and (2*n) % d in [d1, 0, 1]])]) # Chai Wah Wu, Aug 07 2014
(PARI) antidiv(n) = {my(v = []); for (k=2, n1, if (abs((n % k)  k/2) < 1, v = concat(v, k)); ); v; }
a(n) = {my(vad = antidiv(n)); my(nbad = 0); for (j=1, n1, isad = 1; for (k=1, #vad, if ((j % vad[k]) == 0, isad = 0; break); ); nbad += isad; ); nbad; } \\ Michel Marcus, Feb 25 2016


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



EXTENSIONS



STATUS

approved



