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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,3
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COMMENTS
| anti-phi(n) = the number of integers < n that are not divisible by any anti-divisor of n.
The old definition given for this sequence was: anti-phi(n) = number of integers <= n that are coprime to the anti-divisors of n. However this does not match the entries.
See A066272 for definition of anti-divisor.
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LINKS
| Nathaniel Johnston, Table of n, a(n) for n = 2..10000 [This replaces an earlier b-file computed by Diana Mecum]
Jon Perry, Anti-phi function [Broken link]
Jon Perry, The Anti-divisor [Cached copy]
Jon Perry, The Anti-divisor: Even More Anti-Divisors [Cached copy]
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EXAMPLE
| 10 has anti-divisors 3,4,7. The numbers not divisible by any of 3,4,7 and less than 10 are are 1,2,5. Therefore anti-phi(10)=3.
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MAPLE
| antidivisors := proc(n)local a, k:a:={}: for k from 2 to n-1 do if abs((n mod k)- k/2) < 1 then a := a union {k}: fi:od:return a:end:
A066452 := proc(n)local ad, isad, j, k, totad:ad:=antidivisors(n):totad:=0:for j from 1 to n-1 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:
seq(A066452(n), n=2..50); # Nathaniel Johnston, Apr 20 2011
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CROSSREFS
| Cf. A058838, A066241.
Sequence in context: A024994 A051953 A079277 * A007104 A102627 A088296
Adjacent sequences: A066449 A066450 A066451 * A066453 A066454 A066455
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KEYWORD
| nonn,easy
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AUTHOR
| Jon Perry (perry(AT)globalnet.co.uk), Dec 29 2001
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EXTENSIONS
| Better definition and more terms from Diana Mecum (diana.mecum(AT)gmail.com), Jul 01 2007
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