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A283069
A283050(n) divided by the square of its least prime factor.
2
1, 2, 1, 3, 4, 5, 6, 1, 3, 7, 8, 9, 10, 11, 5, 12, 1, 13, 14, 15, 7, 16, 17, 18, 19, 20, 9, 21, 22, 23, 24, 11, 25, 26, 27, 28, 29, 13, 30, 1, 31, 5, 32, 33, 15, 34, 35, 36, 37, 38, 17, 39, 40, 41, 42, 1, 19, 43, 7, 44, 45, 46, 47, 21, 48, 49, 50, 51, 23, 52, 53
OFFSET
1,2
COMMENTS
Sequence contains all positive integers. Every positive integer except 1 can be term of this sequence only finitely many times (i.e., 8 is a term only for a(11) = 8). - Altug Alkan, Feb 28 2017
LINKS
Ana Rechtman, Février 2017, 4e défi, Images des Mathématiques, CNRS, 2017.
FORMULA
a(n) = A283050(n) / A020639(A283050(n))^2. - Altug Alkan, Feb 28 2017
MAPLE
Res:= NULL:
for n from 2 to 1000 do
p:= min(numtheory:-factorset(n));
if n mod p^2 = 0 then Res:= Res, n/p^2; fi
od:
Res; # Robert Israel, Feb 28 2017
MATHEMATICA
DeleteCases[Table[n/FactorInteger[n][[1, 1]]^2, {n, 2, 300}], k_ /; ! IntegerQ@ k] (* Michael De Vlieger, Feb 28 2017 *)
PROG
(PARI) lista(nn) = {for(n=2, nn, if (!(n % (p=factor(n)[1, 1]^2)), print1(n/p, ", ")); ); }
CROSSREFS
Sequence in context: A101204 A169808 A328395 * A304528 A360585 A175499
KEYWORD
nonn,look
AUTHOR
Michel Marcus, Feb 28 2017
STATUS
approved