OFFSET
1,1
COMMENTS
a(n) - a(n-1) >= 8. If a(n-1) = 4*p where p is in A001359 then a(n) - a(n-1) = 8.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(2) = 20, a(3) = 28 = 2^2 * 7 is a triprime and 28 - 20 = 8 = 2^3 is a triprime, and this is the least number > 20 that works, so a(4) = 28.
MAPLE
R:= 8: m:= 8: count:= 1:
for t from 9 while count < 100 do
if numtheory:-bigomega(t) = 3 and numtheory:-bigomega(t-m) = 3 then
R:= R, t; m:= t; count:= count+1
fi
od:
R;
MATHEMATICA
Do[n = m + 8; While[{3, 3} != PrimeOmega[{n, n - m}],
n++]; AppendTo[s, m = n], {100}]; s
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov and Robert Israel, Aug 23 2023
STATUS
approved