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 A098780 First n numbers in binary representation concatenated in reverse order. 5
 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 CROSSREFS Cf. A007088, A047778. Sequence in context: A320089 A239715 A260752 * A222700 A272940 A146178 Adjacent sequences:  A098777 A098778 A098779 * A098781 A098782 A098783 KEYWORD nonn,base AUTHOR Reinhard Zumkeller, Oct 04 2004 EXTENSIONS Typo in data corrected by D. S. McNeil, Aug 20 2010 STATUS approved

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Last modified April 17 11:50 EDT 2021. Contains 343064 sequences. (Running on oeis4.)