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A327900
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Nonprime squarefree numbers whose prime indices all have the same Omega (number of prime factors counted with multiplicity).
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3
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1, 15, 33, 51, 55, 85, 91, 93, 123, 155, 161, 165, 177, 187, 201, 203, 205, 249, 255, 295, 299, 301, 327, 329, 335, 341, 377, 381, 415, 451, 465, 471, 511, 527, 537, 545, 553, 559, 561, 573, 611, 615, 633, 635, 649, 667, 679, 697, 703, 707, 723, 737, 785, 831
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OFFSET
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1,2
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COMMENTS
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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.
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LINKS
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EXAMPLE
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The sequence of terms together with their prime indices begins:
1: {}
15: {2,3}
33: {2,5}
51: {2,7}
55: {3,5}
85: {3,7}
91: {4,6}
93: {2,11}
123: {2,13}
155: {3,11}
161: {4,9}
165: {2,3,5}
177: {2,17}
187: {5,7}
201: {2,19}
203: {4,10}
205: {3,13}
249: {2,23}
255: {2,3,7}
295: {3,17}
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MATHEMATICA
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Select[Range[1000], !PrimeQ[#]&&SquareFreeQ[#]&&SameQ@@PrimeOmega/@PrimePi/@First/@FactorInteger[#]&]
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CROSSREFS
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The case including primes and nonsquarefree numbers is A320324.
The version for sum of prime indices is A327901.
The version for mean of prime indices is A327902.
Cf. A001222, A038041, A056239, A078175, A112798, A306017, A306021, A316413, A317583, A322794, A327908.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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