OFFSET
1,1
COMMENTS
The 4-almost primes are the numbers that are the product of exactly four (not necessarily distinct) primes.
EXAMPLE
a(1)=88=2*2*2*11;
a(2)=1881=3*3*11*19;
a(3)=218812=2*2*11*4973.
MATHEMATICA
d[n_]:=IntegerDigits[n]; t = {x = 88}; Do[i = 1; While[!PrimeOmega[y = FromDigits[Flatten[{z = d[i], d[x], Reverse[z]}]]]==4, i++]; AppendTo[t, x = y], {n, 14}]; t
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Dec 01 2014
STATUS
approved