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A280297 Numbers n such that F(n) and F(n-1) are not squarefree where F(n) = A000045(n).

%I A280297 #24 Aug 08 2025 14:19:23
%S A280297 25,91,126,175,225,276,325,426,456,475,576,625,637,703,726,775,820,
%T A280297 876,925,979,1001,1002,1026,1075,1176,1183,1225,1275,1326,1375,1431,
%U A280297 1476,1525,1548,1625,1626,1675,1729,1776,1825,1926,1975,2076,2094,2125,2148,2226
%N A280297 Numbers n such that F(n) and F(n-1) are not squarefree where F(n) = A000045(n).
%C A280297 Utilized the factorization of Fibonacci numbers in the FactorDB.com database. - _Robert Price_, Feb 27 2017
%H A280297 Robert Price, <a href="/A280297/b280297.txt">Table of n, a(n) for n = 1..108</a>
%H A280297 FactorDB, <a href="http://factordb.com/index.php?query=In&amp;use=n&amp;n=1000&amp;VP=on&amp;VC=on&amp;EV=on&amp;OD=on&amp;PR=on&amp;FF=on&amp;PRP=on&amp;CF=on&amp;U=on&amp;C=on&amp;perpage=20&amp;format=1&amp;sent=Show">Factorizations of F(1000) ... F(1019)</a>.
%e A280297 25 is a term because Fibonacci(25) = 5^2 * 3001 and Fibonacci(24) = 2^5 * 3^2 * 7 * 23.
%o A280297 (PARI) is(n) = !issquarefree(fibonacci(n)) && !issquarefree(fibonacci(n-1));
%Y A280297 Cf. A000045, A013929, A037917.
%K A280297 nonn
%O A280297 1,1
%A A280297 _Altug Alkan_, Dec 31 2016
%E A280297 a(8)-a(108) from _Robert Price_, Feb 27 2017