A338302 a(n) is the first k such that n = Omega(k) = Omega(k-1) + Omega(k+1), or 0 if there is no such k, where Omega is A001222.

2, 4, 8, 56, 80, 624, 1216, 8576, 66176, 59049, 386560, 1476225, 7354880, 58989951, 70184960, 36315136, 8044724224, 39790739456, 53730279424, 96467701761, 2558408523776, 4857090670593, 24607835029504, 177629755867136

Offset

1,1

Comments

a(25) <= 1485324488278016, a(26) <= 3203995725725697. - Daniel Suteu, Mar 28 2021

Links

Table of n, a(n) for n=1..24.

Example

a(3) = 8 because Omega(7)=1, Omega(8)=3, Omega(9)=2 and 1+2=3.

Maple

wp:= 1: w:= 0:
for i from 2 do
  wm:= w; w:= wp; wp:= numtheory:-bigomega(i+1);
  if not assigned(A[w]) and w = wm+wp then
     A[w]:= i;
     if w = 12 then break fi;
  fi
od:
seq(A[i], i=1..12);

Crossrefs

Cf. A001222.

Sequence in context: A058816 A018446 A289324 * A359877 A068620 A073953

Adjacent sequences: A338299 A338300 A338301 * A338303 A338304 A338305

Keyword

nonn,more

Author

J. M. Bergot and Robert Israel, Oct 21 2020

Extensions

a(13)-a(16) from Hugo Pfoertner, Oct 21 2020

a(17)-a(19) from Daniel Suteu, Oct 22 2020

a(20)-a(24) from Daniel Suteu, Mar 28 2021

Status

approved