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a(n) = F(F(F(n))) mod F(F(n)), where F = Fibonacci = A000045.
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%I #15 Nov 14 2020 09:49:59

%S 0,0,0,1,0,5,232,987,1,5,1,0,

%T 2211236406303914545699412969744873993387956988652,

%U 2211236406303914545699412969744873993387956988653,139583862445

%N a(n) = F(F(F(n))) mod F(F(n)), where F = Fibonacci = A000045.

%H Alois P. Heinz, <a href="/A274996/b274996.txt">Table of n, a(n) for n = 1..19</a>

%F a(n) = A058051(n) mod A007570(n).

%p F:= proc(n) local r, M, p; r, M, p:=

%p <<1|0>, <0|1>>, <<0|1>, <1|1>>, n;

%p do if irem(p, 2, 'p')=1 then r:=

%p `if`(nargs=1, r.M, r.M mod args[2]) fi;

%p if p=0 then break fi; M:=

%p `if`(nargs=1, M.M, M.M mod args[2])

%p od; r[1, 2]

%p end:

%p a:= n-> (h-> F(h$2))(F(F(n))):

%p seq(a(n), n=1..15);

%Y Cf. A000045, A007570, A058051, A263101, A263112, A338889.

%K nonn

%O 1,6

%A _Alois P. Heinz_, Nov 11 2016