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A133688
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Least odd primitive abundant number with 3^n as a divisor, but not 3^(n+1).
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0
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5391411025, 5775, 1575, 945, 81081, 78975, 1468935, 6375105, 436444281, 5356826865, 21873816315, 371922783705, 2241870572475, 158639164165575
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OFFSET
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0,1
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LINKS
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EXAMPLE
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5391411025=3^0*5^2*7*11*13*17*19*23*29 least odd abundant number with no factor 3
5775=3^1*5^2*7*11
1575=3^2*5^2*13
945=3^3*5*7
81081=3^4*7*11*13
78975=3^5*5^2*13
1468935=3^6*5*13*31
6375105=3^7*5*11*53
436444281=3^8*7*13*17*43
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PROG
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(PARI)
isprab(v) = {sig = sigma(v); if (sig < 2*v, return (0)); if (sig == 2*v, return (1)); fordiv (v, d, if ((d != v) && (sigma(d)>=2*d), return (0)); ); return (1);
a(n) = {p = 3^n; k = 1; while (1, if (k % 3 != 0, v = p * k; if (isprab(v), return (v)); ); k += 2; ); }
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CROSSREFS
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Cf. A006038 (odd primitive abundant numbers).
Cf. A115414 (odd abundant numbers not divisible by 3).
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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Some terms corrected and more terms from Michel Marcus, Mar 07 2013
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STATUS
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approved
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