A294682 Numbers n such that A294386(n) = 2^(k-1)*(2^k - 2*n - 1) for some k such that 2^k - 2*n - 1 is prime.

0, 12, 62, 121, 126, 205, 241, 877, 1021, 1022, 1645, 2041, 2424, 2761, 2791, 2965, 3355, 3445, 3541, 4021, 4081, 4094, 4165, 4825, 5071, 5191, 5251, 5593, 6151, 6385, 6631, 7465, 7765, 7884, 8137, 8188

Offset

1,2

Links

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

Example

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

Maple

# 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;

Crossrefs

Cf. A096502, A294386.

Sequence in context: A127766 A005173 A196144 * A177677 A045822 A065595

Adjacent sequences: A294679 A294680 A294681 * A294683 A294684 A294685

Keyword

nonn,more

Author

Robert Israel, Nov 06 2017

Status

approved