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Fermat numbers 2^(2^n) + 1 with digits sorted in increasing order and zeros suppressed.
2

%I #8 Apr 11 2021 11:08:12

%S 3,5,17,257,35567,2244677999,111344445566777789,

%T 111222233333334444445666666777788899,

%U 111111222223333333344444455555555566666666777777778888888999999999999

%N Fermat numbers 2^(2^n) + 1 with digits sorted in increasing order and zeros suppressed.

%C The 0, 1, 2, 3, 5 and 7 terms of this sequence are primes. Are there any more?

%t Table[FromDigits[Sort[IntegerDigits[2^2^n+1]]/.(0->Nothing)],{n,0,10}] (* _Harvey P. Dale_, Apr 11 2021 *)

%Y Cf. A000215.

%K base,nonn,nice

%O 0,1

%A _Jason Earls_, Dec 20 2002