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A320461
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MM-numbers of labeled graphs with loops spanning an initial interval of positive integers.
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24
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1, 7, 13, 91, 161, 299, 329, 377, 611, 667, 1261, 1363, 1937, 2021, 2093, 2117, 2639, 4277, 4669, 7567, 8671, 8827, 9541, 13559, 14053, 14147, 14819, 15617, 16211, 17719, 23989, 24017, 26273, 27521, 28681, 29003, 31349, 31913, 36569, 44551, 44603, 46483, 48691
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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. The multiset multisystem with MM-number n is formed by taking the multiset of prime indices of each part of the multiset of prime indices of n. For example, the prime indices of 78 are {1,2,6}, so the multiset multisystem with MM-number 78 is {{},{1},{1,2}}.
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LINKS
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EXAMPLE
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The sequence of terms together with their multiset multisystems begins:
1: {}
7: {{1,1}}
13: {{1,2}}
91: {{1,1},{1,2}}
161: {{1,1},{2,2}}
299: {{2,2},{1,2}}
329: {{1,1},{2,3}}
377: {{1,2},{1,3}}
611: {{1,2},{2,3}}
667: {{2,2},{1,3}}
1261: {{3,3},{1,2}}
1363: {{1,3},{2,3}}
1937: {{1,2},{3,4}}
2021: {{1,4},{2,3}}
2093: {{1,1},{2,2},{1,2}}
2117: {{1,3},{2,4}}
2639: {{1,1},{1,2},{1,3}}
4277: {{1,1},{1,2},{2,3}}
4669: {{1,1},{2,2},{1,3}}
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MATHEMATICA
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primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
normQ[sys_]:=Or[Length[sys]==0, Union@@sys==Range[Max@@Max@@sys]];
Select[Range[10000], And[SquareFreeQ[#], normQ[primeMS/@primeMS[#]], And@@(Length[primeMS[#]]==2&/@primeMS[#])]&]
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CROSSREFS
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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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