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Least n-digit number whose square is exclusionary, or 0 if no such number exists.
3

%I #12 Apr 28 2019 18:05:52

%S 2,17,157,1547,15094,203879,0,0,0

%N Least n-digit number whose square is exclusionary, or 0 if no such number exists.

%C m has an exclusionary square if m consists of distinct digits and m^2 is made up only of digits not appearing in m.

%C a(10) = 0 since 10-digit numbers either use all digits or at least one digit more than once; a(n) = 0 for n > 10 since numbers with more than 10 digits use at least one digit more than once.

%D H. Ibstedt, Solution to Problem 2623 "Exclusionary Powers", Journal of Recreational Mathematics pp. 346-9 Vol. 32 no. 4 2003-4 Baywood NY.

%Y Cf. A112322 (corresponding squares), A110815.

%K nonn,base,fini

%O 1,1

%A _Lekraj Beedassy_ and _Klaus Brockhaus_, Sep 08 2005