%I #20 Sep 24 2024 03:12:50

%S 5391411025,5775,1575,945,81081,78975,1468935,6375105,436444281,

%T 5356826865,21873816315,371922783705,2241870572475,158639164165575

%N Least odd primitive abundant number with 3^n as a divisor, but not 3^(n+1).

%e 5391411025=3^0*5^2*7*11*13*17*19*23*29 least odd abundant number with no factor 3

%e 5775=3^1*5^2*7*11

%e 1575=3^2*5^2*13

%e 945=3^3*5*7

%e 81081=3^4*7*11*13

%e 78975=3^5*5^2*13

%e 1468935=3^6*5*13*31

%e 6375105=3^7*5*11*53

%e 436444281=3^8*7*13*17*43

%o (PARI)

%o 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);}

%o a(n) = {my(p = 3^n, k = 1); while (1, if (k % 3 != 0, v = p * k; if (isprab(v), return (v));); k += 2;);}

%o \\ _Michel Marcus_, Mar 07 2013

%Y Cf. A006038 (odd primitive abundant numbers).

%Y Cf. A115414 (odd abundant numbers not divisible by 3).

%K nonn,more,changed

%O 0,1

%A _Pierre CAMI_, Jan 04 2008

%E Some terms corrected and more terms from _Michel Marcus_, Mar 07 2013