1,2

Table of n, a(n) for n=1..36.

a(3) = 62 is in the sequence because A294386(62) = 192 = 2^6*3 where 2^7 - 2*62 - 1 = 3 is prime.

# Assuming A294386[n] has been assigned for n from 0 to N

Res:= NULL:

for n from 0 to N do

for k from ilog2(2*n+1)+1 do

p:= 2^k - 2*n-1;

if 2^(k-1)*p > A294386[n] then break fi;

if isprime(p) then

if A294386[n] = 2^(k-1)*p then Res:= Res, n fi;

break

fi

od

od:

Res;

Cf. A096502, A294386.

Sequence in context: A127766 A005173 A196144 * A177677 A045822 A065595

Adjacent sequences: A294679 A294680 A294681 * A294683 A294684 A294685

nonn,more

Robert Israel, Nov 06 2017

approved