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A237352
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a(1)=1; for n>1, a(n) is the smallest positive integer for which sigma(a(n)) is a proper multiple of sigma(a(n-1)).
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1
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1, 2, 5, 6, 14, 30, 66, 138, 210, 462, 930, 1974, 3810, 6510, 14322, 26670, 58674, 118110, 245730, 498666, 826770, 1720110, 3784242, 7617630, 15728610, 27524910, 53323410, 110100270, 218453970, 480598734, 853272210, 1877198862, 3413108370, 6772073070
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OFFSET
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1,2
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COMMENTS
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The first term of A090552 that is not here is 11 since sigma(11) equals sigma(a(4)), so it is not a proper multiple.
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LINKS
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PROG
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(PARI) lista(nn) = {n = 1; precs = sigma(n); print1(n, ", "); for (n=2, nn, if ((((ns=sigma(n)) % precs) == 0) && (ns != precs), precs = ns; print1(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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EXTENSIONS
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STATUS
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approved
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