A111730 6-almost primes with semiprime digits (digits 4, 6, 9 only).

64, 96, 4644, 4944, 6664, 6966, 9464, 9996, 44464, 44944, 46496, 46644, 49644, 49696, 64449, 64496, 66444, 66696, 69444, 69496, 69966, 94496, 94644, 94696, 96496, 96944, 99666, 99944, 444496, 444664, 444696, 444996, 446664, 446944, 446964, 449469, 449694, 449964, 464496, 464646, 464664, 464994, 469464, 494494, 494944, 494949, 494964, 496464, 499446, 499944, 644464, 644944

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Example

64 = 2^6
96 = 2^5 * 3
4644 = 2^2 * 3^3 * 43
4944 = 2^4 * 3 * 103
6664 = 2^3 * 7^2 * 17
6966 = 2 * 3^4 * 43
9464 = 2^3 * 7 * 13^2
9996 = 2^2 * 3 * 7^2 * 17
44464 = 2^4 * 7 * 397
44944 = 2^4 * 53^2 = 212^2
46496 = 2^5 * 1453

Mathematica

Select[Range[645000], ContainsOnly[IntegerDigits[#], {4, 6, 9}]&&PrimeOmega[#]==6&] (* James C. McMahon, Jun 05 2024 *)

Prog

(PARI) isok(k) = (bigomega(k) == 6) && (#setminus(Set(digits(k)), Set([4, 6, 9])) == 0); \\ Michel Marcus, Apr 13 2022

Crossrefs

Intersection of A046306 and A107665.

Cf. A001358, A107342, A111494, A111496, A111697.

Sequence in context: A046306 A223086 A175163 * A255990 A104022 A061099

Adjacent sequences: A111727 A111728 A111729 * A111731 A111732 A111733

Keyword

base,less,easy,nonn

Author

Jonathan Vos Post, Nov 18 2005

Extensions

Missing a(1)=64 prepended and several terms corrected by Georg Fischer and Michel Marcus, Apr 13 2022

Status

approved