Search: id:A138769
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%I A138769
%S A138769 1,3,9,33,201,1125,5259,98481,1176579,4970985,83471355,607500315
%N A138769 a(n)=least positive integer k such that k^2+3 is divisible by at least 
               n distinct primes.
%C A138769 The Maple program yields a(7) as well as its 7 prime divisors; change 
               the value of n to obtain other terms.
%D A138769 H. A. ShahAli, Math. Magazine, vol. 81, No. 2, 2008, p. 155, problem 
               1792.
%e A138769 a(3)=9 because 1^2+3=2*2, 2^2+3=7, 3^2+3=2*2*3, 4^2+3=19, 5^2+3=2*2*7, 
               6^2+3=3*13, 7^2+3=2*2*13, 8^2+3=67 have at most 2 distinct prime 
               divisors, while 9^2+3=2*2*3*7 has 3 distinct prime divisors.
%p A138769 n:=7: with(numtheory): for k while nops(factorset(k^2+3)) < n do end 
               do: a[n]:=k; A[n]:=factorset(k^2+3);
%Y A138769 Sequence in context: A009220 A007489 A097677 this_sequence A100076 A148999 
               A149000
%Y A138769 Adjacent sequences: A138766 A138767 A138768 this_sequence A138770 A138771 
               A138772
%K A138769 more,nonn
%O A138769 1,2
%A A138769 Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 03 2008
%E A138769 a(11)-a(12) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Aug 
               31 2008

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