Search: id:a098780
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A098780
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First n numbers in binary representation concatenated in reverse order.
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+0
7
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1, 5, 29, 157, 1437, 13725, 128413, 1176989, 20051357, 355595677, 6261175709, 109340390813, 1896046785949, 32682372363677, 560447953696157, 9567647208437149, 315812421869630877, 10692105963331253661
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) = n*2^(1 + floor(log_2(a(n-1)))) + a(n-1); a(1) = 1.
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EXAMPLE
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a(4) = (4 3 2 1) -> (100 11 10 1) -> 10011101 -> 157.
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MATHEMATICA
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Table[FromDigits[Flatten[IntegerDigits[#, 2]&/@Reverse[Range[n]]], 2], {n, 20}] (* Harvey P. Dale, Sep 10 2019 *)
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PROG
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(Python)
....s=""
....for i in range(n, 0, -1):
........s+=bin(i)[2:]
(Python)
from functools import reduce
def A098780(n): return reduce(lambda i, j:(i<<j.bit_length())+j, range(n, 0, -1)) # Chai Wah Wu, Feb 26 2023
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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