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%I #8 Jul 24 2021 04:24:39
%S 341,561,645,1105,2047,4369,4681,5461,8481,16705,33153,266305,278545,
%T 526593,1052929,1082401,1398101,2113665,2162721,2290641,4259905,
%U 6242685,7674967,8388607,16843009,17895697,22369621,34603041,67371265,268505089,280885153,285212689
%N Fermat pseudoprimes to base 2 that are palindromic in base 2.
%C There are 133 terms below 2^64. Only 4 of them are also Carmichael numbers (561, 1105, 278545 and 67371265).
%H Amiram Eldar, <a href="/A346567/b346567.txt">Table of n, a(n) for n = 1..133</a>
%e 341 is a term since 341 = 101010101_2 is palindromic in base 2, it is composite (= 11 * 31) and 2^340 == 1 (mod 341).
%t pspQ[n_] := CompositeQ[n] && PowerMod[2, n-1, n] == 1; Select[Range[10^6], PalindromeQ[IntegerDigits[#, 2]] && pspQ[#] &]
%Y Intersection of A001567 and A006995.
%Y A065341 and A281576 are subsequences.
%Y Cf. A016041, A068445.
%K nonn,base
%O 1,1
%A _Amiram Eldar_, Jul 23 2021