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Squares of primes with digits in nonascending order.
3

%I #16 Oct 27 2023 18:19:33

%S 4,9,841,961

%N Squares of primes with digits in nonascending order.

%C No other solutions below 4 * 10^18 (probably finite). - Dec 15 1999

%e 961 = 31^2 is in the sequence since its digits (9, 6, 1) are in descending order.

%e 1369 = 37^2 is not in the sequence, since its digits in descending order are: 9, 6, 3, 1.

%t Select[Prime[Range[100]]^2, IntegerDigits[#] == Sort[IntegerDigits[#], Less] &] (* _Alonso del Arte_, Aug 12 2016 *)

%Y Cf. A028868, A028865, A028866.

%K nonn,base,hard,more

%O 1,1

%A _Patrick De Geest_

%E Offset changed by _Altug Alkan_, Sep 09 2016

%E Name clarified by _Jon E. Schoenfield_, Oct 27 2023