login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A138030 Numbers n such that n remains prime through 8 iterations of function f(x) = 2x + 1. 1
85864769, 198479579, 305192579, 2400025739, 7606886429, 7755909149, 10378311899, 16744125509, 17029114499, 17117793089, 17574340739, 26089808579, 28889527679, 43390196519, 45424068359, 52179617159, 54293956289, 56838102179, 65639153579, 66655116659 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..20.

FORMULA

a(n) == 89 or 329 (mod 330). - John Cerkan, Nov 30 2016

MATHEMATICA

Select[Prime[Range[10^8]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[a5=2*a4+1]&&PrimeQ[a6=2*a5+1]&&PrimeQ[a7=2*a6+1]&&PrimeQ[a8=2*a7+1] &]

CROSSREFS

Sequence in context: A186922 A185806 A115534 * A104964 A018787 A003825

Adjacent sequences:  A138027 A138028 A138029 * A138031 A138032 A138033

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 01 2008

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 April 10 15:02 EDT 2021. Contains 342845 sequences. (Running on oeis4.)