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Indices of squares in A068869.
1

%I #17 Feb 17 2023 16:48:56

%S 1,4,5,6,7,8,9,10,11,13,14,15,16

%N Indices of squares in A068869.

%C a(14) > 30000. - _Michel Marcus_, Jan 30 2023

%e 5 is a term because A068869(5) = 1 is a square;

%e 8 is a term because A068869(8) = 81 is a square.

%o (PARI) isok(n) = issquare((sqrtint(n!-1)+1)^2-n!); \\ _Michel Marcus_, Jan 30 2023

%Y Cf. A068869.

%K nonn,more

%O 1,2

%A _Alexander R. Povolotsky_, Jan 29 2023