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 A098780 First n numbers in binary representation concatenated in reverse order. 7
 1, 5, 29, 157, 1437, 13725, 128413, 1176989, 20051357, 355595677, 6261175709, 109340390813, 1896046785949, 32682372363677, 560447953696157, 9567647208437149, 315812421869630877, 10692105963331253661 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Indranil Ghosh, Table of n, a(n) for n = 1..412 FORMULA a(n) = n*A000079(A070939(a(n-1))) + a(n-1); a(1) = 1. a(n) = n*2^(1 + floor(log_2(a(n-1)))) + a(n-1); a(1) = 1. EXAMPLE a(4) = (4 3 2 1) -> (100 11 10 1) -> 10011101 -> 157. MATHEMATICA Table[FromDigits[Flatten[IntegerDigits[#, 2]&/@Reverse[Range[n]]], 2], {n, 20}] (* Harvey P. Dale, Sep 10 2019 *) PROG (Python) def A098780(n): ....s="" ....for i in range(n, 0, -1): ........s+=bin(i)[2:] ....return int(s, 2) # Indranil Ghosh, Jan 28 2017 (Python) from functools import reduce def A098780(n): return reduce(lambda i, j:(i<

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Last modified March 28 03:48 EDT 2023. Contains 361577 sequences. (Running on oeis4.)