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A133688
Least odd primitive abundant number with 3^n as a divisor, but not 3^(n+1).
0
5391411025, 5775, 1575, 945, 81081, 78975, 1468935, 6375105, 436444281, 5356826865, 21873816315, 371922783705, 2241870572475, 158639164165575
OFFSET
0,1
EXAMPLE
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
PROG
(PARI)
isprab(v) = {my(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) = {my(p = 3^n, k = 1); while (1, if (k % 3 != 0, v = p * k; if (isprab(v), return (v)); ); k += 2; ); }
\\ Michel Marcus, Mar 07 2013
CROSSREFS
Cf. A006038 (odd primitive abundant numbers).
Cf. A115414 (odd abundant numbers not divisible by 3).
Sequence in context: A017529 A321497 A335084 * A306497 A115414 A358412
KEYWORD
nonn,more
AUTHOR
Pierre CAMI, Jan 04 2008
EXTENSIONS
Some terms corrected and more terms from Michel Marcus, Mar 07 2013
STATUS
approved