A111697 5-almost primes with semiprime digits (digits 4, 6, 9 only).
464, 496, 696, 944, 4446, 4496, 4664, 6444, 6669, 6996, 9666, 9944, 44649, 44664, 44694, 44696, 44946, 44964, 46664, 46696, 49446, 49496, 49944, 64664, 66664, 66996, 69464, 69944, 69996, 94996, 96464, 96664, 96996, 99664, 99946, 99996
Offset: 1
Examples
a(1) = 464 = 2^4 x 29, a(2) = 496 = 2^4 * 31, a(3) = 696 = 2^3 * 3 * 29, a(4) = 944 = 2^4 * 59, a(5) = 4446 = 2 * 3^2 * 13 * 19, a(6) = 4496 = 2^4 * 281, a(7) = 4664 = 2^3 * 11 * 53, a(8) = 6444 = 2^2 * 3^2 * 179, a(9) = 6669 = 3^3 * 13 * 19, a(10) = 6996 = 2^2 * 3 * 11 * 53.
Links
- Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
Table[Select[FromDigits/@Tuples[{4,6,9},n],PrimeOmega[#]==5&],{n,3,5}]//Flatten (* Harvey P. Dale, Dec 16 2024 *) -
PARI
do(N)=my(v=List(), a=[4, 6, 9]); for(d=1, N, forvec(u=vector(d, i, [1, 3]), t=fromdigits(apply(n->a[n], u)); if(bigomega(t)==5, listput(v, t)))); Set(v) \\ Charles R Greathouse IV, Feb 01 2017
Extensions
Corrected by Ray Chandler, Nov 19 2005