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A245388
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n such that n - tau(n) is a perfect square.
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3
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1, 2, 3, 4, 8, 11, 24, 83, 85, 125, 152, 156, 175, 227, 297, 365, 443, 445, 533, 584, 600, 629, 847, 924, 965, 969, 1036, 1091, 1304, 1308, 1458, 1523, 1612, 1685, 1800, 1853, 1960, 2027, 2316, 2340, 2409, 2605, 2716, 2813, 3029, 3251, 3729, 3973, 4108, 4233
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OFFSET
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1,2
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COMMENTS
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n - tau(n) = A049820(n) is the number of positive integers < n that do not divide n.
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LINKS
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EXAMPLE
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4 - tau(4) = 4 - 3 = 1^2 so 4 is in the sequence.
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MAPLE
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filter:= proc(n) local t;
t:= numtheory:-tau(n);
issqr(n-t)
end proc;
select(filter, [$1..10^4]);
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MATHEMATICA
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PROG
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(Sage)
return is_square(n - a(n))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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