This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A345753 #10 Aug 07 2021 21:39:20
%S A345753 146611,252601,399001,512461,556421,852841,1024651,1193221,1314631,
%T A345753 1857241,1909001,2100901,2165801,2603381,2704801,3470921,3828001,
%U A345753 3942271,4504501,5049001,5148001,5481451,6189121,6840001,7267051,7519441,7879681,8086231,8341201,8719921,9439201,9863461
%N A345753 Euler-Fibonacci pseudoprimes: odd composites k such that F(k) == 5^((k-1)/2) == +-1 (mod k), where F(k) = A000045(k), the Fibonacci numbers.
%C A345753 If p is an odd prime except 5, then F(p) == 5^((p-1)/2) == +-1 (mod p).
%C A345753 All terms found satisfy the congruence F(k) == 5^((k-1)/2) == 1 (mod k). They are a proper subset of A094394.
%C A345753 Are there odd composites m such that F(m) == 5^((m-1)/2) == -1 (mod m)? They are a proper subset (maybe empty) of A094395 (they are not in the database, below 4*10^9).
%t A345753 Select[Range[1, 10^6, 2], CompositeQ[#] && MemberQ[{1, # - 1}, PowerMod[5, (# - 1)/2, #]] && Divisible[5^((# - 1)/2) - Fibonacci[#], #] &]
%Y A345753 Cf. A000045, A094394, A094395, A262052.
%K A345753 nonn
%O A345753 1,1
%A A345753 _Amiram Eldar_ and _Thomas Ordowski_, Jun 26 2021