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%I #28 Jul 25 2023 09:14:40
%S 60,5472,2500704,24361213461200
%N Numbers m such that sigma(m) + tau(m) = 3m.
%C Abundant numbers m with abundance A(m) = m - tau(m) = A049820(m), where A049820(n) is the number of non-divisors of n.
%C Subsequence of A056076.
%C Corresponding values of A(m) = m - tau(m): 48, 5436, 2500632, ...
%C 4 is the only number m with deficiency D(m) = m - tau(m).
%C 808989640739424 is also a term. - _Giovanni Resta_, Nov 14 2019
%e 60 is a term because sigma(60) + tau(60) = 3*60; 168 + 12 = 180 = 3*60.
%t Select[Range[3*10^6], DivisorSigma[0, #] + DivisorSigma[1, #] == 3# &] (* _Amiram Eldar_, Nov 10 2019 *)
%o (Magma) [m: m in [1..10^7] | SumOfDivisors(m) - 2*m eq m - NumberOfDivisors(m)];
%o (PARI) isok(m) = my(f=factor(m)); sigma(f) + numdiv(m) == 3*m; \\ _Michel Marcus_, Nov 13 2019
%Y Cf. A000005, A000203, A033880, A049820, A056076.
%Y Cf. A083874 (numbers m such that sigma(m) + tau(m) = 2m).
%Y Cf. A011251 (numbers m such that sigma(m) + phi(m) = 3m).
%Y Cf. A329104 (numbers m with abundance A(m) = tau(m)).
%K nonn,more
%O 1,1
%A _Jaroslav Krizek_, Nov 10 2019
%E a(4) from _Martin Ehrenstein_, Jul 25 2023
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