The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A084186 First occurrence of exactly n 1's in the binary expansion of sqrt(2). 5
 1, 3, 40, 17, 74, 265, 31, 336, 11937, 1403, 8894, 3524, 33223, 126903, 3067, 109312, 390536, 553171, 280266, 962560, 1747112, 1740081, 30793169, 13109551, 118101037, 1077718187, 44908294, 1528865059, 1647265647, 3913429742, 10501492774, 4702573600, 81557258556, 107498528405 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..34. Nick Hobson, C program EXAMPLE The binary expansion of sqrt(2) is 1.0110101000001..(A004539) and at position 17, there are four 1's, framed by 0's, so a(4)=17. PROG (Python) from itertools import count from math import isqrt def A084186(n): a, b = 2, (1<>1)^1 for k in count(1-n): if isqrt(a)&b==c: return k a<<=2 # Chai Wah Wu, Jan 24 2024 (C) See Links section. CROSSREFS Cf. A084185, A084187. Cf. A233836. Sequence in context: A319955 A317484 A196159 * A037104 A100306 A101014 Adjacent sequences: A084183 A084184 A084185 * A084187 A084188 A084189 KEYWORD base,nonn,hard AUTHOR Ralf Stephan, May 18 2003 EXTENSIONS a(21)-a(29) from Chai Wah Wu, Jan 25 2024 a(30)-a(34) from Nick Hobson, Feb 15 2024 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 23 13:44 EDT 2024. Contains 374549 sequences. (Running on oeis4.)