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A371179 Positive integers with fewer distinct prime factors (A001221) than distinct divisors of prime indices (A370820).

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%I A371179 #5 Mar 20 2024 21:53:35
%S A371179 3,5,7,9,11,13,14,15,17,19,21,23,25,26,27,28,29,31,33,35,37,38,39,41,
%T A371179 43,45,46,47,49,51,52,53,55,56,57,58,59,61,63,65,67,69,70,71,73,74,75,
%U A371179 76,77,78,79,81,83,85,86,87,89,91,92,93,94,95,97,98,99,101
%N A371179 Positive integers with fewer distinct prime factors (A001221) than distinct divisors of prime indices (A370820).
%C A371179 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
%F A371179 A001221(a(n)) < A370820(a(n)).
%e A371179 The terms together with their prime indices begin:
%e A371179      3: {2}        28: {1,1,4}    52: {1,1,6}      74: {1,12}
%e A371179      5: {3}        29: {10}       53: {16}         75: {2,3,3}
%e A371179      7: {4}        31: {11}       55: {3,5}        76: {1,1,8}
%e A371179      9: {2,2}      33: {2,5}      56: {1,1,1,4}    77: {4,5}
%e A371179     11: {5}        35: {3,4}      57: {2,8}        78: {1,2,6}
%e A371179     13: {6}        37: {12}       58: {1,10}       79: {22}
%e A371179     14: {1,4}      38: {1,8}      59: {17}         81: {2,2,2,2}
%e A371179     15: {2,3}      39: {2,6}      61: {18}         83: {23}
%e A371179     17: {7}        41: {13}       63: {2,2,4}      85: {3,7}
%e A371179     19: {8}        43: {14}       65: {3,6}        86: {1,14}
%e A371179     21: {2,4}      45: {2,2,3}    67: {19}         87: {2,10}
%e A371179     23: {9}        46: {1,9}      69: {2,9}        89: {24}
%e A371179     25: {3,3}      47: {15}       70: {1,3,4}      91: {4,6}
%e A371179     26: {1,6}      49: {4,4}      71: {20}         92: {1,1,9}
%e A371179     27: {2,2,2}    51: {2,7}      73: {21}         93: {2,11}
%t A371179 Select[Range[100],PrimeNu[#]<Length[Union @@ Divisors/@PrimePi/@First/@If[#==1,{},FactorInteger[#]]]&]
%Y A371179 The LHS is A001221, distinct case of A001222.
%Y A371179 The RHS is A370820, for prime factors A303975.
%Y A371179 Partitions of this type are counted by A371132, strict A371180.
%Y A371179 Counting all prime indices on the LHS gives A371168, counted by A371173.
%Y A371179 The complement is A371177, counted by A371178, strict A371128.
%Y A371179 A000005 counts divisors.
%Y A371179 A000041 counts integer partitions, strict A000009.
%Y A371179 A008284 counts partitions by length.
%Y A371179 A305148 counts pairwise indivisible (stable) partitions, ranks A316476.
%Y A371179 Cf. A003963, A239312, A285573, A355529, A370802, A370803, A371130, A371165, A371171, A371172.
%K A371179 nonn
%O A371179 1,1
%A A371179 _Gus Wiseman_, Mar 19 2024