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 A180055 In binary expansion, number of 1's in 5n is less than in n. 2
 13, 26, 29, 52, 53, 55, 58, 61, 77, 103, 104, 106, 109, 110, 111, 116, 117, 119, 122, 125, 154, 157, 205, 206, 207, 208, 212, 213, 215, 218, 219, 220, 221, 222, 223, 231, 232, 234, 237, 238, 239, 244, 245, 247, 250, 253, 308, 309, 311, 314, 317, 333, 359, 365 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Or, binary weight of 5n is less than binary weight of n. Also called the 5-flimsy numbers; see the Stolarsky reference. If m is here, 2m is too. Hence the "primitive solutions" are all odd ones: 13,29,53,55,61,77,103,109,111,117,119,125,157,205,207,213,215,219,221,223,231. LINKS Table of n, a(n) for n=1..54. Kenneth B. Stolarsky, Integers whose multiples have anomalous digital frequencies, Acta Arithmetica 38 (2) (1980), 117-128. FORMULA A000120(n) > A000120(5n). MATHEMATICA Select[Range[1000], Count[IntegerDigits[5#, 2], 1]

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Last modified October 2 21:26 EDT 2023. Contains 365840 sequences. (Running on oeis4.)