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 A229120 Inverse of permutation A229119. 2
 1, 3, 2, 7, 6, 5, 15, 14, 4, 13, 10, 31, 30, 12, 29, 9, 26, 21, 63, 62, 28, 61, 8, 25, 58, 11, 18, 53, 42, 127, 126, 60, 125, 24, 57, 122, 17, 27, 50, 117, 22, 37, 106, 85, 255, 254, 124, 253, 56, 121, 250, 16, 49, 59, 114, 245, 19, 34, 54, 101, 234, 20, 45, 74, 213, 170, 511, 510, 252, 509, 120, 249, 506, 48 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Defines an infinite permutation on the integers, containing cycles of infinite length, but with an inverse (A229119) that can be generated. The least integer producing an infinite cycle is n=4 : {4, 7, 15, 29, 42, 37, 17, 26, 11, 10, 13, 30, 127, 77, 242, 266, 173, 205, 2034, 6474, ... LINKS EXAMPLE See A229119. MATHEMATICA << Combinatorica`; unrankpartition[n_Integer, k_Integer] := Block[{ove, res, qq, zz, mem}, ove=PartitionsP[n]-k; res={}; While[n-Tr[res]>0, qq=0; zz=0; While[(mem=NumberOfPartitions[n-Tr[res], qq + 1]) <= ove, zz = mem; qq++]; AppendTo[res, qq + 1]; ove = ove-zz]; res] /; k <= PartitionsP[n] && k > 0; unrankpartition[n_Integer, All]:=Block[{k=1, z}, While[( z=Tr[PartitionsP[Range@k]])

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Last modified June 4 07:23 EDT 2020. Contains 334822 sequences. (Running on oeis4.)