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 A327041 a(n) is the number whose binary indices are the union of the set-system with BII-number n. 19
 0, 1, 2, 3, 3, 3, 3, 3, 4, 5, 6, 7, 7, 7, 7, 7, 5, 5, 7, 7, 7, 7, 7, 7, 5, 5, 7, 7, 7, 7, 7, 7, 6, 7, 6, 7, 7, 7, 7, 7, 6, 7, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS A binary index of n is any position of a 1 in its reversed binary expansion. The binary indices of n are row n of A048793. We define the set-system with BII-number n to be obtained by taking the binary indices of each binary index of n. Every set-system has a different BII-number. For example, 18 has reversed binary expansion (0,1,0,0,1), and since the binary indices of 2 and 5 are {2} and {1,3} respectively, the BII-number of {{2},{1,3}} is 18. LINKS EXAMPLE 22 is the BII-number of {{2},{1,2},{1,3}}, and 7 has binary indices {1,2,3}, so a(22) = 7. MATHEMATICA bpe[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1]; Table[Total[2^Union@@bpe/@bpe[n]]/2, {n, 0, 100}] CROSSREFS Indices of records are A253317. Cf. A000120, A001511, A029931, A035327, A048793, A070939, A072639, A326031, A326702, A326947. Sequence in context: A194225 A025782 A120506 * A277267 A246262 A275974 Adjacent sequences:  A327038 A327039 A327040 * A327042 A327043 A327044 KEYWORD nonn AUTHOR Gus Wiseman, Aug 19 2019 STATUS approved

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Last modified April 21 14:32 EDT 2021. Contains 343154 sequences. (Running on oeis4.)