OFFSET
1,1
COMMENTS
For n >= 2, a(n) is the least semiprime k > a(n-1) such that k - a(n-1) <> a(j) - a(j-1) for j < n.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
R:= 4: x:= 4: S:= {}: count:= 1:
for i from 6 while count < 100 do
if not member(i-x, S) and numtheory:-bigomega(i) = 2 then
R:= R, i; S:= S union {i-x}; x:= i; count:= count+1
fi
od:
R;
MATHEMATICA
s = {4, 6}; df = {2}; Do[k = 1; While [MemberQ[df, k] ||
2 != PrimeOmega[a = s[[-1]] + k], k++]; AppendTo[s, a]; AppendTo[df, k], {98}];
s
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov and Robert Israel, Sep 23 2024
STATUS
approved