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A116991 a(1)=1. a(n) = number of this sequence's terms a(m), 1<= m <= n-1, each with b(a(m),p) not equal to each b(n,p) for every prime p dividing n, where p^b(k,p) is the highest power of the prime p to divide k. 1
1, 1, 2, 3, 4, 3, 6, 7, 8, 7, 10, 7, 12, 7, 9, 15, 16, 13, 18, 15, 10, 16, 22, 16, 24, 18, 26, 21, 28, 14, 30, 31, 22, 22, 22, 29, 36, 24, 26, 31, 40, 14, 42, 35, 33, 29, 46, 32, 48, 32, 37, 44, 52, 36, 41, 41, 43, 38, 58, 36, 60, 40, 46, 63, 51, 32, 66, 57, 49, 35, 70, 59, 72 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Owen Whitby, Table of n, a(n) for n = 1..500

EXAMPLE

Among the sequence's first 11 terms there are 7 terms that share no common prime-power in their prime-factorization with the prime-powers in the prime-factorization of 12. 12 = 2^2 *3^1. The 7 terms sharing no prime-power with 12 are 1, 1, 2, 7, 8, 7 and 10. The other 4 terms (3, 4, 3 and 6) each share at least one prime-power with 12 in the integers' prime-factorizations.

MATHEMATICA

alist={1}; flist={{{1, 1}}}; Do[a=Length[Select[flist, Intersection[ #, FactorInteger[n]]=={}&]]; AppendTo[alist, a]; AppendTo[flist, FactorInteger[a]], {n, 2, 500}]; Print[alist] - Owen Whitby, May 20 2008

CROSSREFS

Sequence in context: A076618 A116550 A283165 * A103634 A255046 A098596

Adjacent sequences:  A116988 A116989 A116990 * A116992 A116993 A116994

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 02 2006

EXTENSIONS

More terms from Owen Whitby, May 20 2008

STATUS

approved

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Last modified October 14 09:25 EDT 2019. Contains 327995 sequences. (Running on oeis4.)