OFFSET
1,2
COMMENTS
Odd numbers k such that Fibonacci(k) is divisible by tau(k).
Includes 15^4 * p for primes p > 5.
LINKS
Robert Israel, Table of n, a(n) for n = 1..250
EXAMPLE
a(3) = 405 is a term because 405 = 3^4 * 5 is odd, tau(405) = 10, and Fibonacci(405) = 1952132532477489958194625524584538730388053593825001030592563956919572392152809678530 is divisible by 10.
MAPLE
filter:= proc(n) uses LinearAlgebra:-Modular; local t, Mt, dt;
t:= numtheory:-tau(n);
if t < 2^25 then Mt:= Mod(t, M, float[8]) else Mt:= Mod(t, M, integer) fi;;
MatrixPower(t, M, n)[1, 2] = 0
end proc:
filter(1):= true:
select(filter, [seq(i, i=1..600000, 2)]);
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Israel, Oct 14 2024
STATUS
approved