|
|
A119529
|
|
Numbers k such that Sum_{j=1..k-1} j*2^(j-1) is prime.
|
|
4
|
|
|
3, 4, 8, 28, 52, 56, 82, 1472, 1484, 8669, 10886, 20804, 32606, 36392, 57005, 61628
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
MATHEMATICA
|
s = 0; Do[s += (x-1)*2^(x-1)/2; If[PrimeQ[s], Print[x]], {x, 10^4}] (* Ryan Propper, Jan 01 2007 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|