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Indices of Fibonacci numbers with 6 distinct prime factors.
3

%I #23 May 05 2024 19:21:42

%S 40,48,54,56,64,78,92,95,99,102,116,117,129,133,155,159,175,177,188,

%T 194,205,206,219,237,245,265,278,314,323,327,339,341,343,346,356,358,

%U 361,362,394,407,411,417,422,427,437,446,454,466,482,502,503,505,514,515,527,535,542,545,551,562,573,577,583,593,607,614,622,623,625,634,655,662,667,674,713,727,731,769,781,789,791,803,809,821,835,893,917,919,974,977,982,993,995,1013,1039,1047,1057,1081,1097,1103,1121,1138,1151,1165,1172,1202,1203

%N Indices of Fibonacci numbers with 6 distinct prime factors.

%C Numbers n such that A000045(n) is in A046306.

%H Amiram Eldar, <a href="/A114839/b114839.txt">Table of n, a(n) for n = 1..123</a>

%H Blair Kelly, <a href="http://mersennus.net/fibonacci/">Fibonacci and Lucas Factorizations</a>.

%e a(1) = 40 because 40th Fibonacci number consists of 6 distinct prime factors (i.e., 102334155 = 3 x 5 x 7 x 11 x 41 x 2161).

%e a(31) = 341 because F(341)= 89 * 557 * 2417 * 761227665342913 * 197907695243868721 * 4558282384863830955384586674337 has exactly 6 prime factors.

%o (PARI) n=1;while(n<330,if(omega(fibonacci(n))==6,print1(n,", "));n++)

%Y Cf. A114823-A114826, A114836-A114841.

%Y Column k=6 of A303217.

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Feb 19 2006

%E More terms from _Jonathan Vos Post_, Mar 22 2006

%E Corrected by _Ryan Propper_, Apr 26 2006

%E a(55)-a(107) from _Max Alekseyev_, Aug 18 2013