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%I #23 Jan 15 2024 00:04:46
%S 1,5,29,157,1437,13725,128413,1176989,20051357,355595677,6261175709,
%T 109340390813,1896046785949,32682372363677,560447953696157,
%U 9567647208437149,315812421869630877,10692105963331253661
%N First n numbers in binary representation concatenated in reverse order.
%H Indranil Ghosh, <a href="/A098780/b098780.txt">Table of n, a(n) for n = 1..412</a>
%H <a href="/index/Mo#MWP">Index entries for sequences related to Most Wanted Primes video</a>
%F a(n) = n*A000079(A070939(a(n-1))) + a(n-1); a(1) = 1.
%F a(n) = n*2^(1 + floor(log_2(a(n-1)))) + a(n-1); a(1) = 1.
%e a(4) = (4 3 2 1) -> (100 11 10 1) -> 10011101 -> 157.
%t Table[FromDigits[Flatten[IntegerDigits[#,2]&/@Reverse[Range[n]]],2],{n,20}] (* _Harvey P. Dale_, Sep 10 2019 *)
%o (Python)
%o def A098780(n):
%o ....s=""
%o ....for i in range(n,0,-1):
%o ........s+=bin(i)[2:]
%o ....return int(s,2) # _Indranil Ghosh_, Jan 28 2017
%o (Python)
%o from functools import reduce
%o def A098780(n): return reduce(lambda i,j:(i<<j.bit_length())+j,range(n,0,-1)) # _Chai Wah Wu_, Feb 26 2023
%Y Cf. A007088, A047778.
%K nonn,base
%O 1,2
%A _Reinhard Zumkeller_, Oct 04 2004
%E Typo in data corrected by _D. S. McNeil_, Aug 20 2010
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