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A019288
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Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (2,11)-perfect numbers.
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9
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OFFSET
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1,1
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COMMENTS
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See also the Cohen-te Riele links under A019276.
53283599155200, 2914255525994496 and 3887055949004800 are also terms. - Michel Marcus, Feb 27 2020
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LINKS
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PROG
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(PARI) isok(n) = sigma(sigma(n))/n == 11; \\ Michel Marcus, Feb 27 2020
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CROSSREFS
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Cf. A019278, A019279, A019281, A019282, A019283, A019284, A019285, A019286, A019287, A019289, A019290, A019291.
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KEYWORD
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nonn,bref,more
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AUTHOR
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STATUS
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approved
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