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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A225890 Composite numbers n such that A179382((n+1)/2)=(n-1)/(2^c) for some c > 0. 1
92673, 143713, 3579553, 4110529, 28688897, 127017857, 141127681, 157648097, 162101441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(10) > 180*10^6. All terms up to a(9) are of the form 32*k+1 and except a(1) are also semiprimes. The numbers 212999489, 393300097 and 663414881 are also terms. - Giovanni Resta, May 21 2013

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

143713=137*1049: A179382((143713+1)/2)=4491=(143713-1)/(2^5)

PROG

(PARI) oddres(n)=n>>valuation(n, 2)

cyc(d)=my(k=1, t=1); while((t=oddres(t+d))>1, k++); k

p=5; forprime(q=7, 1e7, forstep(n=p+2, q-2, 2, my(t=(n-1)/cyc(n), c=valuation(t, 2)); if(t>>c==1 && c>0, print1(n", "))); p=q) \\ Charles R Greathouse IV, May 20 2013

CROSSREFS

Cf. A179382.

Sequence in context: A182657 A251069 A184560 * A183853 A128277 A237682

Adjacent sequences:  A225887 A225888 A225889 * A225891 A225892 A225893

KEYWORD

nonn,more

AUTHOR

Lear Young and Peter Košinár, May 20 2013

EXTENSIONS

Missing a(3) from Giovanni Resta, May 20 2013

a(6)-a(9) from Giovanni Resta, May 21 2013

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 26 06:48 EDT 2019. Contains 321481 sequences. (Running on oeis4.)