login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A274524 Numbers n such that both ror(n) and rol(n) are squares, where ror(x)=A038572(x) is x rotated one binary place to the right, rol(x)=A006257(x) is x rotated one binary place to the left. 1
1, 2, 8, 32, 128, 512, 1568, 2048, 2312, 2592, 2888, 8192, 16928, 32768, 131072, 139392, 250632, 524288, 549152, 566048, 672800, 924800, 963272, 1318688, 2097152, 8388608, 8520192, 8769672, 9005768, 12261152, 13582472, 15635232, 33554432, 134217728, 136059008, 136587392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A004171 and A081294 are subsequences.

From Robert Israel, Jul 13 2016: (Start)

All terms except 1 are even.

Even terms are the numbers of the form n = (a+b)^2/8 such that for some d >= 1,

2^d <= n < 2^(d+1) and 2^(d+1)-1 = a*b. (End)

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

F:= proc(d) local v, R, X;

      v:= 2^(d+1)-1;

      R:= select(t-> t^2 < v, numtheory:-divisors(v));

      op(select(t -> t >= (v+1)/2 and t < v+1, map(t -> (t+ v/t)^2/8, R)));

end proc:

sort(convert({1, seq(F(i), i=1..50)}, list)); # Robert Israel, Jul 13 2016

MATHEMATICA

Select[Range[10^6], Times @ Boole@ {IntegerQ@ Sqrt@ FromDigits[RotateRight@ #, 2], IntegerQ@ Sqrt@ FromDigits[RotateLeft@ #, 2]} &@ IntegerDigits[#, 2] == 1 &] (* Michael De Vlieger, Jun 29 2016 *)

CROSSREFS

Cf. A006257, A038572, A004171, A081294.

Sequence in context: A282879 A217665 A320654 * A081294 A004171 A009117

Adjacent sequences:  A274521 A274522 A274523 * A274525 A274526 A274527

KEYWORD

nonn,base

AUTHOR

Alex Ratushnyak, Jun 27 2016

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 22 01:38 EDT 2018. Contains 316431 sequences. (Running on oeis4.)