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A250435
Numbers whose squares remain squares when prepended with 9 and appended with 25 in base 10.
3
30, 12834, 18141477989940702510, 48095105831852088000, 5437693915503684117819750, 5784962279163039331595016, 864479870564593025822726220, 24351951618610295127241673897127630, 25652594148194488759500411647073225254466
OFFSET
1,1
EXAMPLE
30^2 = 900, 990025 = 995^2.
MAPLE
F:= proc(d) local m, D, P;
m:= 9*10^d+25;
D:= numtheory:-divisors(m);
P:= map(t -> (m/t - t)/20, select(t -> t^2 < m and (m/t - t) mod 20 = 0, D));
op(select(t -> 10^(d-3) <= t^2 and t^2 < 10^(d-2), P));
end proc:
seq(F(n), n=4..83); # Robert Israel, Apr 04 2017
KEYWORD
nonn,base,more
AUTHOR
Chai Wah Wu, Nov 23 2014
STATUS
approved