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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
Cf. A000523.
Sequence in context: A168382 A155701 A353950 * A366812 A180629 A258372
KEYWORD
nonn,more
AUTHOR
Jorge Coveiro, Jul 27 2006
EXTENSIONS
a(10) from Ryan Propper, Jan 01 2007
Name simplified by Jon E. Schoenfield, Sep 23 2018
a(11)-a(14) from Amiram Eldar, Dec 01 2021
a(15)-a(16) from Michael S. Branicky, May 04 2023
STATUS
approved

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Last modified February 22 06:21 EST 2024. Contains 370240 sequences. (Running on oeis4.)