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A275449 Least odd primitive abundant number with n prime factors, counted with multiplicity. 2

%I

%S 945,7425,81081,78975,1468935,6375105,85930875,307879299,1519691625,

%T 8853249375,17062700625

%N Least odd primitive abundant number with n prime factors, counted with multiplicity.

%C See A188342 = (945, 3465, 15015, 692835, 22309287, ...) for the least odd primitive abundant number (A006038) with n distinct prime factors.

%C At least up to a(11), the greatest prime factor gpf(a(n)) = Q(a(n)/gpf(a(n))), where Q(N) = floor(sigma(N)/(2N-sigma(N))). In general one has to apply the precprime() function A007917 to this integer.

%C The above holds also for a(12)-a(15). _Lars Blomberg_, Apr 09 2018

%e We have: a(5) = 945 = 3^3 * 5 * 7,

%e a(6) = 7425 = 3^3 * 5^2 * 11,

%e a(7) = 81081 = 3^4 * 7 * 11 * 13,

%e a(8) = 78975 = 3^5 * 5^2 * 13,

%e a(9) = 1468935 = 3^6 * 5 * 13 * 31,

%e a(10) = 6375105 = 3^7 * 5 * 11 * 53,

%e a(11) = 85930875 = 3^6 * 5^3 * 23 * 41,

%e a(12) = 307879299 = 3^7 * 7^2 * 13^2 * 17,

%e a(13) = 1519691625 = 3^8 * 5^3 * 17 * 109,

%e a(14) = 8853249375 = 3^8 * 5^4 * 17 * 127,

%e a(15) = 17062700625 = 3^9 * 5^4 * 19 * 73.

%o (PARI) a(n)=for(i=1,#A=A006038,bigomega(A[i])==n&&return(A[i])) \\ Provided that A006038 is defined as a set with enough elements. - _M. F. Hasler_, Jul 27 2016

%Y Cf. A006038, A188342, A188439.

%K nonn,more

%O 5,1

%A _M. F. Hasler_, Jul 27 2016

%E a(12)-a(15) from _Lars Blomberg_, Apr 09 2018

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Last modified June 2 11:20 EDT 2020. Contains 334771 sequences. (Running on oeis4.)